Phy 213: General Physics III 6/14/2007 Chapter 30 Worksheet 1

Size: px

Start display at page:

Download "Phy 213: General Physics III 6/14/2007 Chapter 30 Worksheet 1"

Maurice Sharp
6 years ago
Views:

1 Phy 13: General Phyic III 6/14/007 Chapter 30 Workheet 1 Faraday Law of Electromagnetic Induction and Lenz Law 1. For the following cenario, determine whether the magnetic flux change or tay the ame. If the flux change: indicate whether it i increaing or decreaing (and in which direction). Explain your anwer. a. he magnet i held tationary to the olenoid. = 0 b. he magnet i moving toward the olenoid. increaing c. he magnet i moving away from the olenoid. decreaing. Find the direction of the induced current for the olenoid in the figure below, when the magnet i. a. tationary to the olenoid. i=0 b. moving toward the olenoid. counter-clockwie c. moving away from the olenoid. clockwie

2 Phy 13: General Phyic III 6/14/007 Chapter 30 Workheet 3. circular loop (radiu of 10 cm or 0.10 m) i placed in a uniform magnetic field of magnitude, =.0, where the face of the loop i perpendicular to the direction of the magnetic field. =.0 (out of page) a. Determine the magnetic flux through the loop. Φ = d = co φ = 0.68 m b. he loop i then rotated 90 o in 3.0 econd. What i the magnetic flux through the loop at the end of the 3.0 econd? Φ = d = co φ = 0 m c. What i the induced emf in the loop during the rotation? 0.68 m 3 m =- = = ( or V) 4. peron move a -m rod at a contant velocity of 3 m/ in a magnetic field, =.0. he rod i perpendicular to the direction of the field. a. What i the direction of induced current in the rod? in the +z direction b. Determine the induced emf in the rod. W F L qvl = = = =vl= 1 V q q q c. he reitance in the rod (and connecting wire) i -Ω. What i the current in the rod? 1V i = = = 6 R Ω d. Determine the magnitude and direction of the magnetic force acting on the rod. F =il =- 4 ˆi e. Determine the force the peron exert on the rod to keep it in motion. F =F +F =0 F = -F = 4 ˆi net hand hand i v = 3 m/ z y x

3 Phy 13: General Phyic III 6/14/007 Chapter 30 Workheet 3 5. Conider a 1-m conducting rod attached at each end by conducting rail. he rail are connected at the top and the total loop ha a reitance of 5-Ω. (ee figure below). he rod fall to the ground at a contant velocity, v. he apparatu i inide a contant magnetic field, = 3.0 (directed out of the page). he ma of the rod i 0.5kg. = 3.0 (out of page) R = 5 Ω 1 m v = contant a) What i the magnetic force on the falling rod, due to the magnetic field? F = F - mg = mg ˆj = 4.9 ˆj net b) What i the induced current in the rod? φ F 4.9 L (1m)(3) F = ilin = 4.9 i = = = 1.63 c) What i the induced electromotive force,? = ir = (1.63)(5 Ω ) = 8.15 V d) What i the equation for the rate of change of magnetic flux for thi problem? d d(lh) dh = = = L = Lv = - e) How fat i the rod falling? ˆ 8.15 V ˆ m v = - j = - j = -.7 ˆ j L 3 m f) When the rail fall for 1 ec, verify that energy i conerved. P mg = P mgv = i i v = =.71 mg m, check with (e)

Phy 13: General Phyic III 6/14/007 Chapter 30 Workheet 4 Generator 6. water powered generator, hown below, to convert mechanical energy into electrical energy.

4 Phy 13: General Phyic III 6/14/007 Chapter 30 Workheet 4 Generator 6. water powered generator, hown below, to convert mechanical energy into electrical energy. rotating wheel receive falling water forcing a wire loop (=500), located within a contant magnetic field =0.01 (a hown), to rotate counter-clockwie at a rate of 150 rpm. he length of the egment normal to the field (ide a) are 0.0 m and the length of the egment parallel to the field (ide b) i 0.15 m. a. What i the area of the region of the coil within the magnetic field? = ab = (0.15m)(.0m) = m b. Determine the general equation for the magnetic flux through the coil in term of area,, and angular velocity ω. Φ = d= co ω t c. What i the angular velocity ω of the rotating coil? 1 min π rad = 150 min = rot rot ω ( ) d. Calculate the induced electromotive force around the loop. ( ω ) =- =- co t 0 avg 0 avg d rad ω inωt 4 = = - coωt = - = -1.5 V a b he intantaneou emf i: (t)= ωin( ωt+ φ ) e. What direction doe the induced current flow around the coil? Explain. he current will flow clockwie (looking down on the armature), in accordance with RHR.

5 Phy 13: General Phyic III 6/14/007 Chapter 30 Workheet 5 elf Inductance: 7. olenoid, r=0.01 m, l=0.03 m (length) and =100, i in erie with a 10 Ω reitor, both of which are in parallel with a 10 Ω reitor, all of thee are in erie with a 5 V power upply. a. Determine the inductance, L, of the olenoid. µ -6 L = o = 3.96x10 H b. When the power upply i initially connected. What i the current acro the olenoid? i o-olenoid = 0 c. What i the initial current drawn from the power upply? i = o V R = 0.50 d. fter 1 minute, what i the current through the olenoid? 60 -Rt 5V - L -7 olenoid max ( ) ( ) 3.96x10 i = i 1-e = 1-e = Ω e. What i the total current drawn from the power upply? i tot = 1.00 f. How much energy i tored in the inductor after 1 minute? U = ½Li = 4.95x10-7 J V 10 Ω L 10 Ω

Magnetism Lecture Series. Electromagnetic Induction

Magnetism Lecture Series. Electromagnetic Induction Magnetim Lecture Serie Electromagnetic Induction Applied Science Education Reearch Group (ASERG) aculty of Applied Science Unieriti Teknologi MARA email: jjnita@alam.uitm.edu.my; drjjlanita@hotmail.com