Unit C. Electromagnetic Energy ( )( ) Chapter 1: Electric and Magnetic Fields. Practice, page 314. Practice, page 316. Practice, page 321

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1 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. Unit C Electromagnetic Energy Chater : Electric and Magnetic Field Practice, age 34. The ath of lightning i determined by ocket of ionized air molecule in the atmohere. Since the air ocket are not evenly aced and are randomly ditributed, the ath of the lightning trike i not a traight line. ntead, lightning trike are jagged, following the ocket of ionized air molecule.. a. f the air ha a high moiture content, it will releae more energy a water vaour condene into drolet. The added energy ha the effect of heating u the arcel of air, which caue it to rie even higher. b. A riing column of water vaour ruhe at a column of decending water drolet. Since water molecule in the drolet hold onto their electron more tightly than water molecule in the vaour, the water drolet become negatively charged by collecting electron from ome of the water molecule. A the drolet fall, the bottom of the cloud become negatively charged and the to of the cloud become oitively charged. 3. a. Since the ebonite rod gained electron, it i aid to be negatively charged. 0 b. q rod. 4 0 electron. 00 C electron. 0-9 C The ebonite rod would have a charge of C. Note that the charge on the rod i negative ince the rod gained electron. Practice, age a. q 5 C D E? E D q D E q ( )( ) J/C 5 C J The lightning trike delivered J of energy. b. The value of the electrical energy delivered by the lightning trike in quetion 4.a. i nearly 80% of the value of the electrical energy ued by a tyical Alberta home in one month. Although thee energy value are very imilar, a key difference i that the energy in a lightning trike i delivered in a fraction of a econd, while the electrical energy ued by the houe i ued over one full month. Practice, age 3 5. a. Tree and ridge roject into the air and are likely location for lightning trike. n an oen field, a hiker could be the highet oint and, therefore, a otential target for a lightning trike.

2 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. b. The hiker are illutrated in an area of low ground and are hown itting down to avoid making themelve art of the hortet ath for the lightning. Additional recaution include itting on their ack and keeing metal gear away from their bodie. Thee recaution hel reduce the oibility of a hiker becoming art of the conducting ath. 6. hen a coma i ued to determine direction, the only influence on the magnetic coma needle hould be Earth magnetic field. Object containing iron, cobalt, and nickel could influence the coma needle in a way that caue it to give an inaccurate reading. 7. The eak of a mountain i farther from the centre of Earth than the bae of the mountain, o the gravitational field line are lightly farther aart at the eak than at the bae. The low concentration of gravitational field line at the eak indicate that the gravitational field i weaker at thi location. 8. Tye of Field electric magnetic gravitational General Decrition of Source for Thi Field Source object are either oitively or negatively charged. Source object are either magnet or electric current. Source object have ma.. Quetion, age 36 and 37 General Decrition of Tet Bodie for Thi Field Tet bodie are mall charged object. Tet bodie are mall magnet, uch a coma needle. Tet bodie are mall object with ma. Two Examle of a Source for Thi Field the negative charge on the bottom of a thundercloud the metal grid on a bug zaer a current-carrying coil in a eaker a fridge magnet Earth the Sun Knowledge. a. An object ha a negative charge if it ha more electron than roton. Thi i uually created by the object gaining exce electron from ome other object. b. An object ha a oitive charge if it ha fewer electron than roton. Thi i uually created by the object loing electron to ome other object. c. A coulomb i an S unit for charge, where one coulomb i equivalent to the tranfer of electron. d. Electric otential difference i the change in otential energy er unit of charge. e. oltage i another term for electric otential difference. f. A volt i a unit for voltage, where J/C. g. An electric field i a roerty of the ace around a ource charge that enable the ource charge to exert force on other charge that enter thi region.

3 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. h. A magnetic field i a roerty of the ace around a magnet or an electric current that enable the magnet or electric current to exert force on other magnet, uch a coma needle, that enter thi region. i. A gravitational field i a roerty of the ace around a ource ma that enable the ource ma to exert force on other mae that enter thi region. j. A tet body i an obervable object that can exerience a force due to the reence of a field. The nature of the tet body i matched to the tye of field that it i able to detect mall mae are the tet bodie for gravitational field, mall charge are the tet bodie for electric field, and tiny magnet (like coma needle) are the tet bodie for magnetic field. k. Field line are a attern of line that decribe the direction of a field by the way they oint and the trength of a field by their denity.. Electric, magnetic, and gravitational field have the following characteritic in common: A ource object i able to exert a force on a tet object without any hyical contact. The field can be decribed in term of field line. The field are inviible. Electric, magnetic, and gravitational field have the following differing characteritic: The ource and tet object for each field differ. Electric, magnetic, and gravitational field involve interaction between object that have charge, magnetic ole, and ma, reectively. The field line for each tye of field form different tye of attern. Electric field line can oint toward or away from a ource, deending uon the nature of the ource charge. Magnetic field line form loo that are directed from the north ole to the outh ole. Gravitational field line alway oint toward the ource. 3. Field are comletely inviible. They can only be oberved indirectly through their effect on matter. The articular characteritic of the matter that allow a field to be oberved define the characteritic of the tet body for that field. Tet bodie for electric, magnetic, and gravitational field have charge, magnetic ole, and ma, reectively.

4 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. Alying Concet 4. a. and b. N bar magnet magnetic field oitively charged here electric field S Earth moon gravitational field negatively charged balloon electric field two charged late electric field

5 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. 5. a. Since the child lot ome of the electron from her body to the latic material of the layground lide, he became oitively charged, while the lide became negatively charged. b. c. The voltage develoed a a child goe down a lide i a large value over Thi mean that J of energy are tored for every coulomb of charge that i tranferred between the child and the lide. The fact that not many coulomb of charge are tranferred mean that the energy i relatively mall large enough to give an unleaant hock, but not large enough to be life-threatening. Practice, age 39 electric field line 9. A oitively charged article would tend to attract electron that are held by molecule. n ome cae, the electron could be removed from a covalent bond between two atom within the molecule, cauing the chemical bond to break and the tructure of the molecule to change. 0. A you learned in Unit A, the DNA molecule conit of two trand of nucleotide. The trand are aid to be comlementary becaue the hohate bae in a nucleotide on one trand will only bond with a certain bae from a nucleotide on the other trand. Comlementary bae airing for DNA are adenine with thymine and cytoine with guanine. f a fat-moving charged article damage an adenine bae on one trand of DNA, there i only one way for the cell to reair thi damage becaue the thymine bae on the other trand will only bond with a relacement adenine bae. However, if an ionized article break both trand, the bluerint for an accurate reair ha been detroyed. f the cell randomly add the ame number of bae that were detroyed by the ionized article, the reult could be a oint mutation. f the cell attemt a reair by imly rejoining the broken trand without ubtituting for the detroyed bae, the reult i a more eriou framehift mutation. A you learned in Unit A, mutation uch a thee can caue the death of the cell or can lead to dieae uch a cancer. Practice, age 333. f the exonent wa forgotten and the value for ditance wa not quared, the denominator of the fraction would have too mall a value. Thi mean that the value for gravitational field trength would be much too large.

6 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. Practice, age 334. Location 7 r m g Gm r 4 - m kg ( Nim /kg ) g? m N/kg The gravitational field trength of Earth at location i N/kg. Location ( kg) ( ) 4 8 r m g Gm r 4 - m kg ( Nim /kg ) g? m N/kg The gravitational field trength of Earth at location i N/kg. Location ( kg) ( ) 4 8 r m g Gm r 4 - m kg ( Nim /kg ) g? m N/kg ( kg) ( ) 4 The gravitational field trength of Earth at location i N/kg. Location 8 r m m g? 4 kg g Gm r - ( Nim /kg ) m N/kg ( kg) ( ) 4 The gravitational field trength of Earth at location i N/kg.

7 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. 3. Location 7 r m m g? kg g Gm r - ( Nim /kg ) m N/kg ( kg) ( ) The gravitational field trength of the Moon at location i N/kg. Location 6 r m m g? kg g Gm r - ( Nim /kg ) m.45 N/kg The gravitational field trength of the Moon at location i.45 N/kg. 4. a. to c. Earth g Earth N/kg ( kg) ( ) Location Moon. gmoon N/kg d. The gravitational field trength of the Moon i N/kg, directed toward the Moon. The gravitational field trength of Earth i N/kg, directed toward Earth. The trength of thee two gravitational field are the ame, but they act in ooite direction. e. f a ace vehicle come to ret and turn off it engine at location, both the Moon and Earth would exert the ame gravitational force on it becaue the trength of the gravitational field from each object i the ame. However, becaue the gravitational field act in ooite direction, the force would alo act in ooite direction and would cancel out. 5. a. f the ditance from Earth double, the value of the denominator in the gravitational field trength equation i increaed by a factor of 4. Thi i due to the fact that the value of r i doubled and then quared, o the overall effect i r i 4 time larger. Since the denominator i 4 time larger, the gravitational field trength i only 4 of it reviou value. b. f the ditance from Earth increae by a factor of 0, the value of the denominator in the gravitational field trength equation i increaed by a factor of 00. Thi i due to the fact that the value of r i made 0 time larger and then quared, o the overall effect i r i 00 time larger. Since the denominator i 00 time larger, the gravitational field trength i only 00 of it reviou value.

8 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. Practice, age a. q C r midoint E? 0. 0 m E kq r 9 ( Nim /C )( C) 0.0 m ( ) The trength of the electric field at the midoint due to the here on the left i N/C. b. The direction of the electric field at the midoint due to the here on the left i to the right becaue thi i the way that a oitive tet charge would be forced. c. Since the value for ource charge and ditance are the ame, the electric field trength will have the ame value for the here on the right a for the here on the left: N/C. However, the direction of the electric field i to the left, ince thi i the way that a oitive tet charge would be forced by the ource charge on the right. d. The electric field of the ource charge on the left i N/C, right. The electric field of the ource charge on the right i N/C, left. Since thee two vector are equal but ooite, the electric field cancel. Practice, age a. The diagram howing the electric field around the balloon hould look imilar to the one given. N/C

9 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. b. Calculate the electric field trength due to one balloon at the midoint. r cm m 00 cm 0. m q nc C E? E kq r ( Nim /C ) m 99 N/C ( ) - ( C) 9 9 The trength of the electric field at the midoint due to one balloon i 99 N/C. Determine the direction of the electric field vector. For the balloon on the left, the electric field due to thi ource charge will oint to the left, ince thi i the way a oitive tet body would be forced. For the balloon on the right, the electric field due to thi ource charge will oint to the right, ince thi i the way a oitive tet body would be forced. Combine the reult from the calculation and analyi to tate the final anwer. midoint 99 N/C 99 N/C Since the electric field of one balloon i equal in magnitude but ooite in direction to the electric field of the other balloon, the electric field vector cancel. The reult i the net electric field i zero. Practice, age Magnetic field can be roduced by electric current and by ermanent magnet. n the cae of a coil with an electric current aing through the loo of wire, it i moving charge that form the electric current; o, ultimately, moving charge are the ource of the magnetic field. n the cae of a ermanent magnet, the inning motion and orbital motion of electron within the atom of the magnetic material form the moving charge. f the motion of the electron can be organized o that the magnetic field are aligned, it i a if each electron contribute to the magnetic field of a bar magnet in the ame way that each loo of wire contribute to the magnetic field of a coil. Thi i why the reulting magnetic field of a bar magnet i identical to that formed by a current-carrying coil.

10 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. 9. efer to the Labelling the Magnetic Field Around a Current-Carrying Coil Labelled handout. Practice, age The major challenge in NASA lan i roviding energy for the charged oitive here and the current-carrying coil that will be oitioned above the bae. at amount of electrical energy would need to be generated on a continuou bai.. Earth inhabitant are rotected from the harmful effect of charged article from the olar wind and comic radiation by Earth magnetic field and the hielding effect of the atmohere.. Quetion, age 346 to 348 Knowledge. a. Mar m r km 000 m km g? m kg g Gm r - ( Nim /kg ) m N/kg N/kg The gravitational field trength on the urface of Mar i 3.70 N/kg. o m r. 8 0 km 000 m km g? m kg ( kg) ( ) 3 g Gm r - ( Nim /kg ) m N/kg. 80 N/kg ( kg) ( ) The gravitational field trength on the urface of o i.80 N/kg. 0

11 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. b. Mar c. Mar g N/kg m 00 kg F g? F g mg ( 00 kg )( N/kg) 370 N The force of gravity on thi atronaut would be 370 N on the urface of Mar. o o g N/kg m 00 kg F g? F g mg ( 00 kg )( N/kg) 80 N The force of gravity on thi atronaut would be 80 N on the urface of o. d. The ma and radiu value for Mar reult in a larger gravitational field trength on the urface of Mar than on the urface of o. Since the gravitational field trength i larger, the gravitational field line are drawn cloer together and the force on a 00-kg atronaut i greater on Mar than it would be on o.

12 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age.. a. van de Graaff Generator q 3. 5 mc r 8 cm m 00 cm 0. 8 m E? - 6 C E kq r ( Nim /C ) m ( ) N/C ( C) 9 6 The trength of the electric field on the urface of the van de Graaff generator i N/C. Balloon q nc r 7 cm m 00 cm 0. 7 m E? - 9 C E N/C kq r ( Nim /C ) m ( ) N/C ( C) 9 9 N/C The trength of the electric field on the urface of the balloon i N/C. b. van de Graaff Generator Balloon

13 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. c. van de Graaff Generator E N/C - q C F e? F E q e - ( N/C) ( C) The magnitude of the electric force on the dut eck i N. Since the dut eck i negative and the van de Graaff globe i oitive, the force on the dut eck will be toward the van de Graaff globe. F e N, toward the van de Graaff generator Balloon E N/C - q C F e? - 6 N F E q e - ( N/C) ( C) 5. 0 The magnitude of the electric force on the dut eck i N. Since the dut eck i negative and the urface of the balloon i negative, the force on the dut eck will be away from the urface of the balloon. 3. a. S F e N, away from the balloon b. N - 9 N c. S N Alying Concet 4. a. Gravitational field alway oint toward the ource object. So, at the location of ACE, the direction of the gravitational field of the Sun i toward the Sun. b. Gravitational field alway oint toward the ource object. So, at the location of ACE, the direction of the gravitational field of Earth i toward Earth. c. The gravitational field vector are ulling ACE in ooite direction. Although the gravitational field of the Sun i larger, the gravitational field of Earth i able to reduce the effect of thi field by cancelling out a ortion of the Sun gravitational field. 3

14 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. 5. a. The oitively charged comonent act a a oitive ource object for an electric field. Since a oitively charged tet object that come cloe to thi ource would be reelled, the direction of the electric field line i away from the oitively charged comonent. b. Since ooite charge attract, the negatively charged electron on nearby comonent would be attracted to the oitively charged ource. c. No, the anwer to quetion 5.a. and 5.b. do not contradict one another. The anwer to quetion 5.a. decribe the direction of the force on a oitively charged tet body. Electric field are alway decribed in term of oitively charged tet bodie. The anwer to quetion 5.b. decribe the direction of the force on a negatively charged electron. t make ene that the direction in quetion 5.a. and 5.b. hould be ooite becaue the tet bodie have ooite charge. 6. The information from the ACE webite would be very ueful to the tour oerator becaue it would enable them to monitor change in the olar wind. The olar wind i the henomenon that ower the northern light. Sudden increae in olar-wind activity could indicate that the ace weather i more likely to roduce northern light, making the condition ideal for a night of oberving them. Practice, age 350. hen a large eaker i generating ound wave, the movement of the eaker cone may be inviible to your eye; yet, if you gently lace your fingerti on the outide edge of the eaker cone, you can feel the vibration. 3. a. A microhone convert the mechanical energy of ound wave into the energy of an electrical ignal. A headhone tranform the energy in an electrical ignal into the mechanical energy of ound wave. b. Your ene of hearing involve the ame baic roce a a microhone the mechanical energy of vibration i converted into an electrical ignal. However, in the cae of hearing, the electrical ignal i tranmitted biochemically through nerve cell intead of through wire. Practice, age q. 0 C t 30 min 60 min ? q t 4. 0 C C/ 6. A The quantity of energy that ae through the wire egment a the motor i running i 6. A. 5. An adequate uly of electrical energy would allow for the oibility of large refrigeration unit in centralized food-torage facilitie. The refrigeration unit could be ued to tore food that might otherwie oil if it were tored at higher temerature. Having le food lot due to oilage would be an imortant firt te in making more food available to the local oulation. 4

15 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. Practice, age Motor The armature of thi motor ha a outh ole at the to of the coil and a north ole at the bottom of the coil. The outh ole will dro to the left becaue it i attracted to the north ole of the fixed magnet. The north ole will rie to the right becaue it i attracted to the outh ole of the fixed magnet. The rotation that reult from the interaction of the magnetic ole would aear to be counterclockwie when viewed from the front of the armature haft. Motor The armature of thi motor ha a north ole at the to of the coil and a outh ole at the bottom of the coil. The north ole will dro to the left becaue it i attracted to the outh ole of the fixed magnet. The outh ole will rie to the right becaue it i attracted to the north ole of the fixed magnet. The rotation that reult from the interaction of the magnetic ole would aear to be counterclockwie when viewed from the front of the armature haft. Motor 3 The armature of thi motor ha a outh ole at the to of the coil and a north ole at the bottom of the coil. The outh ole will dro to the right becaue it i attracted to the north ole of the fixed magnet. The north ole will rie to the left becaue it i attracted to the outh ole of the fixed magnet. The rotation that reult from the interaction of the magnetic ole would aear to be clockwie when viewed from the front of the armature haft. 7. Thi device take an inut of electrical energy and convert it into the mechanical energy of the rotating haft. Since the haft i connected to the blade of a fan, the energy of the haft i tranferred to the kinetic energy of the moving fan blade. The turning fan blade then do work on the urrounding air, creating the kinetic energy of moving air, otherwie known a a breeze. 8. The inide urface of one magnet hould be a north ole, and the inide urface of the other magnet hould be a outh ole. 9. a. The iece of the motor identified in te 5 i called the armature. b. The three earated contact on the end of the axle are called the commutator. c. The iron coil intenifie the magnetic field of each coil in much the ame way a nail can intenify the magnetic field roduced by the coil of a imle electromagnet. d. Three coil would have everal advantage. One advantage i that at leat one coil would alway be in a oition to exerience a large magnetic force due to the interaction with the fixed magnet on the metal caing. n the imle tudent-built motor, the ingle coil wa in a oition to exerience a large force only during a mall ortion of a full rotation. Another advantage of three coil i that the motor would be le likely to get tuck in one oition. ecall your work from the Building an Electric Motor. Since thi motor had one coil, it ometime got tuck in one oition becaue the coil haened to align with the two fixed magnet. The three-coil ytem make thi kind of alignment imoible, o the motor can t get tuck in one oition. 5

16 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. 30. a. The metal contact are called bruhe. b. The bruhe are made from thin material that i light and ring-like o contact can be maintained with the commutator while alying light reure to allow the armature to rotate eaily..3 Quetion, age 364 and 365 Knowledge. Device i a generator becaue the inut i mechanical energy (ulied by the falling aer cli) and the outut i electrical energy, a meaured by a voltmeter. Since thi generator ha li ring, it will act a a ource of alternating current and i, therefore, an AC generator. Device i a DC motor becaue the inut i electrical energy (ulied by an electrochemical cell) and the outut i mechanical energy in the form of riing aer cli. Device 3 i a generator becaue the inut i mechanical energy (ulied by the falling aer cli) and the outut i electrical energy, a meaured by a voltmeter. Since thi generator ha a lit-ring commutator, it will act a a ource of direct current and i, therefore, a DC generator.. a. rotating coil e. li ring b. bruh f. lit-ring commutator c. voltmeter g. voltage ource d. ermanent magnet h. lit-ring commutator Alying Concet 3. mechanical energy headhone microhone electrical energy 4. The north ole of the armature will be attracted to the outh ole on the inide urface of the magnet on the left. Thi mean that the armature will rotate counterclockwie when viewed from the front. 5. The motor will continue to turn in the ame direction becaue when the art of the armature that i currently on to i rotated to the lower left, the lit in the commutator will align with the bruhe. Even though the current will continue to flow through the armature at thi oint, the inertia of the inning armature will carry it at until the current i re-etablihed. hen the current i re-etablihed, it will witch direction becaue the bruhe are touching different egment of the commutator, cauing the art of the armature that ued to be a north ole to become a outh ole. The outh ole will be reelled by the inide urface of the magnet on the right, o the armature will continue to rotate in the ame direction. hen the art of the armature that wa originally on the to reache the bottom, the cycle reeat ince a north ole will once again be formed at the to of the armature. 6

17 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. 6. The device hown i an AC generator, o the outut i an alternating current. 7. f the number of armature rotation er minute i increaed, the outut of the generator ha a higher frequency and the voltage eak are higher. Practice, age 369 t t 3. The following anwer decribe the error in the circuit hown on the handout Multimeter Troublehooting. a. There are two error with thi attemt to meaure current: The meter i not connected in erie with the device. The to inut lead of the meter i not et to meaure current. b. The meter i not connected in erie with the device to meaure current. The on the dilay indicate that the current entering the meter i beyond the 0-mA cale that wa elected on the dial of the meter. The uual outcome of thi kind of error i that a fue i blown in the meter. c. Although the meter i correctly connected, the dilay read 0.00 becaue the fue in the meter ha blown. The circumtance decribed in quetion 3.b. i the uual event that caue thi ort of roblem. d. There are two error with thi attemt to meaure voltage: The meter i not connected in arallel with the device. The to inut lead of the meter i not et to meaure voltage. e. The oitive lead of the meter i connected to the negative ide of the circuit, while the negative lead of the meter i connected to the oitive ide of the circuit. Thi roblem can be corrected by revering the outut lead of the ower uly or by revering the inut lead of the meter. 7

18 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. Practice, age a. Since the light bulb i connected directly to the houehold circuitry, the current aing through the bulb i AC. b A? The reitance through the bulb i A a. The light bulb i oerated by the batterie of the flahlight, o the current aing through the bulb i DC. b /A? The current through the bulb i 0.75 A. Practice, age ? /A A For voltage ource in erie, The voltage of the four cell connected in erie i cell combo 4-cell combo? For voltage ource in arallel, 4-cell combo 4-cell combo 4.4 The voltage for the two four-cell combination i

19 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. Practice, age a. b ? For voltage ource in erie, + The voltage available to thi circuit i.0. c ? For reitor in erie, + The reitance available to thi circuit i ? A The current flowing through the circuit i 0.0 A. Since the bulb are connected in erie, the current flowing through each bulb i the ame a the current, 0.0 A. d A? ( 0.0 A )( 0 ) A 40? ( 0.0 A )( 40 ) 8.0 The voltage acro reitor i 4.0. The voltage acro reitor i 8.0. e. f one bulb burn out, the current i interruted for the whole circuit. Since no current i available for the other bulb, it will not be lit either. 37. a ? 6. 0 Since the voltage ource are equal and connected in arallel, the voltage i equal to the voltage acro one ource. 9

20 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. b. 0 c. 40? The reitance of the two bulb i ? 3. 3 For reitor in arallel, + ( 0 ) + ( 40 ) ( ) ( ) /A 0.45 A The current flowing through the whole circuit i 0.45 A. d. Determine the current flowing through A 3. The current running through A 3 i the current flowing through the whole circuit, which i 0.45 A. Determine the current flowing through A. te : Since the reitor are connected in arallel, the voltage acro i the ame a the voltage. Therefore, 6.0. te : Now, olve for, the current flowing through ? /A 0.30 A The current flowing through i 0.30 A. 0

21 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. te 3: Determine the current flowing through A. Since A and are connected in erie, the current flowing through A i identical to the current flowing through. Therefore, the current flowing through A i 0.30 A. Determine the current flowing through A. te : Since the reitor are connected in arallel, the voltage acro i the ame a the voltage. Therefore, 6.0. te : Now, olve for, the current flowing through ? The current flowing through i 0.5 A. te 3: Determine the current flowing through A /A 0.5 A Since A and are connected in erie, the current through A current through 0.5 A. e. After flowing through ammeter, the current mut divide. One art flow through ammeter ; the other art flow through ammeter. f. f one of the bulb burn out, the other light bulb i till able to emit light becaue there i more than one ath for the current in a arallel circuit. Practice, age a. Blender Toater 60 0? A 0? 0 0 A The current flowing through the blender i.0 A. The current flowing through the toater i 0 A.

22 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. Kettle 0 0? 0 0 A The current flowing through the kettle i A. b. The current required by all three device would be 4 A. c ? The reitance of all the device i 5.0. d ? A The current required by all the device i 4 A. Thi value i conitent with the anwer to quetion 38.b. e. f all three device are witched on at the ame time, the current flowing through the circuit would be 4 A. The maximum afe current for houehold circuit like thi i 5 A. hen the current exceed thi value, the circuit breaker tri, hutting down the whole circuit. f. Each device that i witched on rovide another new ath for current to flow. Since more current i able to flow, the current ha increaed and the effective reitance of the whole circuit ha been decreaed. Thi i not a contradiction becaue even though a new device bring it own reitance to the circuit, the fact that a new ath ha been added act to lower the reitance.

23 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age..4 Quetion, age 384 Knowledge. All electric circuit require a ource of voltage, connecting wire, and at leat one device that convert electrical energy into other form of energy.. The exreion relate the variable for voltage, current, and reitance. 3. a. f the voltage i doubled, the value of the current i doubled. b. f the reitance i doubled, the value of the current i halved. 4. a. hen voltage ource are connected in erie, the voltage i doubled, roviding more energy to the circuit. b. hen voltage ource are connected in arallel, the voltage i unchanged, but now two ource can hare the burden of ulying energy to the circuit. Thi mean that if the voltage ource are batterie, they will lat twice a long. t alo mean that if one ource fail, the other can till rovide energy to the circuit. 5. a. hen electrical device are connected in erie, the energy drawn from the ource of voltage i reduced. b. hen electrical device are connected in arallel, each device i able to be witched off and on indeendently of the other device in the circuit. 6. Anwer may vary. One oibility i hown here. Serie Circuit The ame current flow through each comonent connected in erie Parallel Circuit The current flowing into a number of comonent connected in arallel i equal to the um of the current flowing through each of the comonent The voltage acro a number of comonent connected in erie i equal to the um of the voltage value acro the individual comonent The reitance of a number of comonent connected in erie i equal to the um of the reitance value of the individual comonent The ame voltage exit acro each comonent connected in arallel The reitance of a number of comonent connected in arallel i given by the following equation:

24 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. Alying Concet ? /A A The current that flow through the reitor i A ? /A A The current that flow through the comonent i A. 9. a. b..0.0? For a erie connection, The voltage for the batterie connected in erie i ? For a arallel connection,. 0 The voltage for the batterie connected in arallel i a ? For a erie connection, The reitance for the two reitor connected in erie i

25 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age.. a. b ? For a arallel connection, ( ) + ( ) The reitance for the reitor connected in arallel i b. i ? A For reitor in erie, The reitance of the circuit i ii ? /A A 0.38 A The current flowing through each reitor i 0.38 A. 5

26 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age.. a. iii A? The voltage acro i A 80.0? The voltage acro i.. ( A )( ) 6.9 ( A )( ). iv. f reitor burned out, the whole circuit would to functioning. f there i only one ath for current and that ath i broken, the current to flowing..50 b. i ?.50 A 500 For reitor in arallel, ( ) + ( ) The reitance of the circuit i 333. ii ? For voltage ource in arallel,. 50 The voltage of the cell i.50. 6

27 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. iii ? /A A or 4.50 ma The current flowing through the circuit i A or 4.50 ma. iv. All the comonent are connected in arallel, o the voltage value hould all be equal. Therefore, the voltage acro i.50 and the voltage acro i.50. v. f the 500- reitor burned out, current would till be able to flow through the 000- reitor. 3. hen device are connected in arallel, the voltage value acro the device are the ame. Since a voltmeter i ued to meaure a voltage acro a device, it make ene that the voltmeter i connected in arallel o that the tet lead of the meter will be at the ame voltage a the device when they make contact. hen device are connected in erie, the current flowing through each device i the ame. Since an ammeter i ued to meaure current through a device, it make ene that the ammeter i connected in erie o that the ame current will flow through the ammeter a the other device. Practice, age a. Firt Model of efrigerator P J/ 60 min t 6. 0 h 60 h min 600 P E t E Pt ( 700 J/ )( 600 ) J E? The energy ued by the firt model i J. Second Model of efrigerator P J/ 60 min t 6. 0 h 60 h min 600 P E t E Pt ( 500 J/ )( 600 ). 0 7 J E? The energy ued by the econd model i. 0 7 J. 7

28 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. b. The manufacturer of the 500- model i able to claim that the model i an environmentally friendly alternative becaue thi refrigerator will ue le energy over it lifetime of ue than the 700- model. Thi mean that thi model will have le imact in term of negative environmental conequence due to generating electricity. Practice, age P. 00 A P? (. 00 A ) ( 4. 0 ) 6 The ower conumed by the eaker i 6. Thi confirm that the one-te aroach reult in the ame anwer a the two-te aroach. 4. te : Calculate the voltage acro the wire of the eaker A? ( A )( 4. 0 ) 8 The voltage acro the wire of the eaker i 8. te : Calculate the ower conumed by the eaker A P? P ( A )( 8 ) 8 The ower conumed by the eaker i 8. Thi confirm that the two-te aroach reult in the ame anwer a the one-te aroach. 4. a. circuit breaker

29 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. b c. 8. 0? The reitance of the two eaker i 4.0. P max max 5. 0 A ( ) ( ) P? max max ( 5. 0 A ) ( 4. 0 ). 0 0 The maximum ower conumed by the eaker i.0 0. d. Method : Uing P Method : Uing P A? P P A A? 4. 0 ( 5. 0 A )( 4. 0 /A) 0 The voltage ulied to thi circuit i 0. The voltage ulied to thi circuit i a. circuit breaker b ? The reitance of the two eaker in thi circuit i

30 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. c ? /A. 5 A The current drawn by the eaker in thi circuit i.5 A. d.. 5 A 0. 0 P? P (. 5 A )( 0. 0 ) 5. 0 The ower conumed by the two eaker in thi circuit i a. f the goal wa to roduce the mot ound energy from the 0- inut ignal, the bet arrangement would be to have the eaker connected in arallel. The arallel circuit ha a ower rating of.0 0, which mean thi arrangement of the eaker will ue.0 0 J of electrical energy every econd. The erie circuit ha a ower rating of only 5, o it would ue 5 J of electrical energy every econd. b. The diadvantage relate to the fact that the arallel arrangement draw quite a large amount of current from the ound ytem. t would be imortant to know whether other comonent can handle uch a large current. n ome cae, circuitry in other comonent (like amlifier) can be damaged if a large amount of current run through them. The large current alo mean that if the car engine i hut off and the tereo i running directly from the car battery, the arallel arrangement would drain the battery ooner than the erie circuit. Practice, age The anwer to thi quetion will vary deending uon the articular aliance that haen to be in your home. The following lit rereent ome of the mot common device. device with electronic dilay and oft-touch keyad, uch a microwave oven, coffee maker, tove, and dihwaher device with remote control, uch a C, DD layer, T, tereo receiver, CD layer, and garage door oener device that ue AC adater, uch a mall handheld vacuum cleaner, cordle hone, comuter router, comuter modem, and ome comuter eaker ytem 30

31 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. 46. a. P 87 k k t 365 d 4 h d h E? P E t E Pt 3 ( h) (. k) kih kih The energy ued by all the device that ue tand-by ower i kih. b. unit of energy 76. kih cot er unit of energy 9. 3 /kih cot of energy? $ /kih cot of energy unit of energy cot er unit of energy ( )( ) 76. kih $ /kih $ $ 7 The cot of maintaining tand-by ower for thi houehold i about $7. c. The reviou calculation how that although the amount of tand-by ower ued by one device may eem trivial, the cumulative effect of many of thee device can be ignificant for a houehold. f thi line of thinking i taken farther by multilying by all the houehold in Alberta, then by all thoe in Canada, and finally by all thoe in develoed countrie, the reult i a huge amount of electrical energy that mut be generated to uly all thee device with tand-by ower. The generation of electricity ha an imact on the environment. n many lace, including Alberta, electricity i generated by burning foil fuel, which add carbon dioxide and other emiion to the atmohere. f the electricity i generated by hydroelectric generator or by huge wind turbine, there are till environmental conequence becaue thee facilitie mut be ituated, built, and maintained at ome lace in the environment. Practice, age a. CO (g) Emitted 4 unit of energy kih g 3 kg emiion rate. 0 0 kih 000 g. 0 kg/kih ma emitted unit of energy emiion rate ( kih). 0 kg/kih. 0 4 kg ( ) ma emitted? Thi family account for. 0 4 kg, or.0 t, of CO (g) emiion due to their electricity ue. 3

32 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. SO x (g) Emitted 4 unit of energy kih g kg emiion rate. 9 kih 000 g kg/kih ma emitted? ma emitted unit of energy emiion rate ( kih) kg/kih 0 kg Thi family account for 0 kg of SO x (g) emiion due to their ue of electricity. NO x (g) Emitted 4 unit of energy kih g kg emiion rate. 4 kih 000 g kg/kih ma emitted? ( ) ma emitted unit of energy emiion rate ( kih) kg/kih 5 kg Thi family account for 5 kg of NO x (g) emiion due to their ue of electricity. Particulate Matter Emitted 4 unit of energy kih g kg emiion rate 0. 4 kih 000 g kg/kih ma emitted? ( ) ma emitted unit of energy emiion rate ( kih). 4 0 kg/kih. 5 kg ( ) Thi family account for.5 kg of articulate matter emiion due to their ue of electricity. 4 b. unit of energy.05 0 kih cot of energy 8. 8 /kih $ /kih cot unit of energy cot of energy ( ) ( ) kih $ / kih $94 Thi family annual cot of electrical energy i $94. 3

33 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. 48. a. P 85 k k t 365 d 4 h d h E? P E t E Pt 3 ( ) (. ) k h kih kih Every year, thi family conume kih of electrical energy to maintain tand-by ower for the device in their home. b. electrical energy kih energy for tand-by ower kih ercentage ued for tand-by ower? energy for tand-by ower ercentage ued for tand-by ower 00% energy kih 00% kih 7.% Aroximately 7.% of thi family annual electricity ue can be traced to the conumtion of tand-by ower. Since the ma of the emiion are all deendent uon the amount of electrical energy ued, if 7.% of thi energy i attributed to tand-by ower, then tand-by ower account for 7.% of emiion. 49. There are a number of trategie thi family could conider to reduce their environmental emiion. One trategy i to reduce carele conumtion by turning off device that are not being ued. Thi trategy would include turning off light, televiion, and radio that are not being ued. Another trategy i to chooe more energy-efficient model when device need to be relaced. Examle would include relacing conventional light bulb with the comact fluorecent tye and relacing older aliance with model that ue le energy. A final trategy i to avoid uing device that oerate with exceive amount of tand-by ower. Although it may be difficult to find a microwave oven that doe not have a digital clock and a ofttouch keyad, it i imortant to let manufacturer and retailer know that conumer lace a high value on energy efficiency. Many manufacturer have reonded to thee demand by roducing roduct line that addre thee concern. 33

34 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. Practice, age a. Thi device i a te-down tranformer becaue the voltage i being reduced from 4.00 k in the rimary coil to 40 on the econdary coil. b. N N c k 000 k ? 3 N N N N 3 ( )( 80) There are turn of wire on the rimary coil of thi tranformer A? 3 ( 00 A )( 40 ) The current ulied to the tranformer i 6.00 A. 5. a. Thi device i a te-u tranformer becaue the voltage i being increaed from 0.0 k to 30 k. b. The utility comany boot the 0.0-k voltage from the generator to even higher value to reduce loe due to the heating of the cable during tranmiion. Since the equation that decribe the ower conumed by heating loe within the tranmiion cable i P, the value of the current ha a huge imact on ower loe becaue current i quared in the equation. However, in order to tranmit the electrical energy, a combination of current and voltage i till required, a decribed by the equation P. Since the current value mut be minimized, the voltage value i maximized. Thi arrangement allow the tranmiion of large amount of ower with minimal loe due to heating effect. A c. P k k M 6 0. M. 0? 6 5 P P P ia A 5. A The current flowing through the tranmiion cable i 5. A. 34

35 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. d k k A? ( )( A) 60 A The generator i ulying 60 A of current to the tranformer at the generating tation. e. n an ideal tranformer, the ower rating of the econdary coil and the rimary coil are equal. Therefore, P P. M. 0 6 The ower equation can now be ued to determine the current flowing in the rimary coil. P k 000 k. 00 0? 6 4 P P P A The current flowing through the rimary coil i 60 A. ia.5 Quetion, age 403 Knowledge. t i mileading to call a bill from a utility comany a ower bill becaue the bill i charging the cutomer for the electrical energy ued, not for the rate of uing energy, which i ower.. n a te-u tranformer, the inut voltage on the rimary coil mut be increaed to a larger value on the econdary coil. n order for thi to haen, the econdary coil mut have more turn of wire. Alying Concet 3. There i no hyical connection between the circuit of the rimary coil and the circuit of the econdary coil. The only link between thee two circuit i the magnetic field that exit within the common core of both coil. Jut a a generator work when there i a changing magnetic field within the loo of the coil on it armature, a current can be induced to flow in the econdary coil only if a magnetic field i changing within the loo of the econdary coil. The alternating current in the rimary coil enure that the magnetic field within the core i alway changing. Thi changing magnetic field then roduce an alternating current in the econdary coil. Thee are the reaon why both the rimary coil and the econdary coil of a tranformer oerate with alternating current. 35

36 Science Alberta Education ( Third-arty coyright credit are lited on the attached coyright credit age. 4. Calculate the current ? /A A The current flowing through the toater i 8.57 A. Calculate the ower A P? The toater will diiate of ower. 5. Calculate the energy required. P 5. 0 k k t 365 d 4 h d h A P ( A )( 0 ) P E t E Pt 3 ( h) (. k) kih E? The energy required by the clock in one year i 43.8 kih. Calculate the cot. unit of energy kih cot er unit of energy 8. 7 /kih cot of energy? $0.087/kih cot of energy unit of energy cot er unit of energy ( 43.8 kih )( $0.087/kih) $ 3. 8 The cot of the energy to oerate the clock for one full year i $