1 NAME PERIOD GUIDESHEET UNIT 2 WORK SUBUNIT - WORK IN ELECTRICAL SYSTEMS ACTIVITY LESSON DESCRIPTION SCORE/POINTS 1. NT ELECTRICAL CONCEPT NOTES (worksheet) /30 NT ELECTRICAL WORK CLASS NOTES (worksheet /20 2. TX Reading guide for pages 106-116 /59 3. WS CROSSWORD PUZZLE /13 4. SE STUDENT EXERCISES /16 5. MS MATH PRACTICE WORKSHEET /24
2 5 points for filling in all the notes Electrical concepts notes Write at least 5 study questions From the notes (5 points) All objects are If an atom has a equal number of and then the object is neutral - has no charge Electrons on the outer part of atoms are Amount of effort it takes to remove the electrons depends Removing electrons then puts STATIC ELECTRIC CHARGES 1. CHARGING BY FRICTION AND CONTACT Rubber holds tighter than fur. Rub a balloon with fur, electrons move. The balloon has a static electric charge, and the fur has a charge. Rub a glass or plastic rod with silk. The silk the electrons and becomes charged, the glass or plastic rod becomes. You scuff off your feet while walking across a carpet. When you touch a door handle, you get a shock as electrons are attracted to your 2. CHARGING BY DIRECT CONTACT Charged can charge other through direct contact. 3. CHARGING BY INDUCTION. Charging by induction occurs in. Charges build up in the clouds. charges go to the top of the cloud, and charges build up at the bottom of the cloud.
5 points for filling in all the notes The charges at the bottom, 3 Write at least 5 study questions From the notes (5 points) induce a build up of charges on the ground. These charges will leak off If too much charge builds up, then Lightening rod are placed on buildings to If a charged object is brought near, electrons don't migrate or leave, but the This is how a balloon sticks to the wall. (Draw Picture) Other demonstrations: (describe)
4 5 points for filling in all the notes MAGNETISM, ELECTRICITY AND MOVEMENT There is a relationship between these 3 things. Write at least 5 study questions From the notes (5 points) Any will produce the 1. a magnet in a coil of wire - you get (like in ) 2. electricity in a wire - you get (like in ) 3. an electric current around a magnet, - you will get (like in a ) increase or decrease voltage depending how the wires are coiled around the transformer. (Draw Example) If there is volts in one coil on the left and 10 coils on the right, then volts comes
5 off the right. 5 points for filling in all the notes WORK IN ELECTRICAL SYSTEMS NOTES Write at least 5 study questions From the notes (5 points) causes a charge to move. W = ΔV x q ΔV = q = W = volt coulomb = joule is used to measure work in mechanical, fluid, electrical and thermal systems. Example How much work is done to recharge a battery if a constant voltage difference of 12 V moves 8000 coulombs of charge? Coulombs are hard to measure. Easier to measure the rate that the coulombs move. Rate is called Example Given: a DC motor operates for 2 minutes (120 seconds) on a voltage of 12 V while drawing a current of 4 amps. Find the work done for the 2 minutes. (120 seconds)
5 points for filling in all the notes Example Given: An automobile solenoid on a starter is active for 1.2 seconds. It draws a current of 15 amps at 12 volts. 6 Write at least 5 study questions From the notes (5 points) Volts are measured with a It is places outside the circuit and you measure the voltage difference across 2 places. (Draw picture) measure amps. It is placed in the circuit so the current flows through it. (Draw Picture) Electrical work produces: Electrical Efficiency: Motors convert work into work. Some electric work is lost as heat (motor gets hot) Example Given a motor does 5760 Joules of work to lift a 2000 N beam a height of 2.5 meters. Find efficiency.
7 WORKSHEET PP. 106-116 1. A force does work on an object when it does what? (1) 2. In an electrical system, the forces are applied to by. (2) 3. The presence of a potential difference can result in moving and doing in an electrical system. (2) 4. You can't see electrical work being done, you can only see the of electrical work. (1) 5. are a source of potential difference. (1) 6. Electric charge is measured in (1) 7. One coulomb of charge is equal to the charge of electrons. This is the same as 6.25 electrons.(2) (Skip p. 109) 8. Write the equation for electrical work and tell what the letters stand for. (4) 9. Potential difference is measured in. (1) 10. One Volt Coulomb = one. (1) 11. Electric fields and potential difference are created when there is a what? (1) 12. Look at example 2.8 on page 111, then do the following problem: An automobile battery is being charged. 900 C of charge are deposited in the battery by an average potential difference of 9 Volts. How much work is done by the charger. (4 pts) 13. The amount of charge (Coulombs) can't be measured easily. It's more practical to measure, or. (2) 14. Current is measured in per (2) 15. A flow of one coulomb per second (C/s) is called an (1)
8 16. A device for measuring current is called an (1) 17. Write the equation to show what current equals in words and with letters. (4) 18. One coulomb equals one. If one ampere of flows for one, one of charge is moved past a point in a circuit. (4) 19. What are electric relays and solenoids used for? (1) 20. What are 3 ways electric motors are used? (3) 21. Another result of charge movement by voltage is the production of. (1) 22. Give 2 examples of where the production of heat is wanted. (2) 23. Give 2 examples of where the production of heat is not wanted (2) 24. Light is produced when: (1) 25. How are radio waves, TV signals, and microwaves related to light? (1) 26. Sound from speakers of electronic devices is a result of what? (1) 27. Efficiency of any electrical device is defined by what equation? (3) 28. Write the steps in the process that show how electricity is produced at electrical generation stations. (4) 32. The overall efficiency of this conversion process is less than (1) 33. List 4 good reasons for using electricity. (4)
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Math Practice worksheet For each problem: Write the formula, show your work, write the answer and label (4 points each) 12 Electric work = Volts x charge W = V q Charge = amps x time (coulombs) q = I t (or q = A t) %E = WO x 100 WI 4 pts 1. Five coulombs of charge flow in an electrical circuit. The charge is pushed by a voltage difference of 8 volts. Find the work done. 4 pts 2. A 6 volt DC motor does 400 joules of useful work. Find the charge that was moved to do this work. 3. A motor/pump unit does 1500 Nm of work while pumping water. The motor/pump unit uses 1800 joules of electric energy while doing the work. Find the efficiency of the motor/pump unit. 4 pts 4. An industrial motor does 1500 joules or work while moving 50 coulombs of charge. Find the voltage supplied to the motor. 4 pts 5. Two coulombs of charge are moved by a 6 volt battery. Find the electrical work done. 4 pts 6. A motor runs for 80 seconds drawing a current of 4 amps at a voltage of 7 volts. Find the electrical work done. (solve for charge, then plug that into the formula for work) 4 pts