assignment, Sample
Create 57112, Homework 13, Sep 01 at 11:29 am This print-out should have 11 questions. Multiple-choice questions may continue on the next column or page nd all choices before answering. The due time is Central time. Covers 29.1-29.3 Induced EMF in a Coil 31:01, calculus, numeric, > 1 min, normal. 001 A 30 turns circular coil with a radius 4 cm and a resistance 1 is placed in a magnetic eld directed perpendicular to the plane of the coil. The magnitude of the magnetic eld varies in time according to the expression B = a 1 t + a 2 t2 , where a1 = 0.01 T/s, a2 = 0.04 T/s2 are constants, time t is in seconds and eld B is in Tesla. Calculate the magnitude of the induced E in the coil at t = 5 s. Answer in units of V. Applied Force on a Bar 02 31:02, trigonometry, numeric, > 1 min, wording-variable. 002 In the arrangement shown in the gure, the resistor is 5 and a 4 T magnetic eld is directed out of the paper. The separation between the rails is 3 m . Neglect the mass of the bar. An applied force moves the bar to the left at a constant speed of 2 m/s . Assume the bar and rails have negligible resistance and friction. 4T m 1g 3m I 5 2 m/s
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003 At what rate is energy dissipated in the resistor? Answer in units of W. Car Antenna 31:02, trigonometry, numeric, > 1 min, normal. 004 A car with a 1 m long radio antenna travels at 80 km/h in a place where the Earths magnetic eld is 5 105 T. What is the maximum possible induced emf in the antenna as it moves through the Earths magnetic eld? Answer in units of V. Ro d Sliding on a Ring 02 31:02, calculus, numeric, > 1 min, normal. 005 A metal bar is sliding across the surface of a metal ring, as shown in the gure. There is a uniform magnetic eld directed into the paper. 50 cm/s 0.05 T
10 c
m
0.05 T What is the magnitude of the induced emf, E , in the rod when it is a distance 6 cm from the center of the ring? Answer in units of V. Lenzs Law 02 31:03, trigonometry, multiple choice, < 1 min, xed. 006 A magnetic eld that is decreasing with time is directed out of the page and passes through a circular loop of wire in the plane of the page. Which of the following is true of the induced current in the wire loop? 1. It is counterclockwise in direction.
4T Calculate the applied force required to move the bar to the left at a constant speed of 2 m/s. Answer in units of N.
Create assignment, 57112, Homework 13, Sep 01 at 11:29 am 2. It is clockwise in direction. 3. It is directed into the page. It 4. is directed out of the page. 5. It is zero in magnitude. Reshap e the Wire 31:04, calculus, numeric, > 1 min, normal. 007 A circular wire loop of radius 0.5 m lies in a plane perpendicular to a uniform magnetic eld of magnitude 0.4 T. In 0.1 s the wire is reshaped into a square but remains in the same plane. What is the magnitude of the average induced emf in the wire during this time? Answer in units of V. Serway CP 20 21 31:04, trigonometry, numeric, > 1 min, normal. 008 An automobile has a vertical radio antenna 1.2 m long. The automobile travels at 65 km/h on a horizontal road where Earths magnetic eld is 50 T directed toward the north and downward at an angle of 65 below the horizontal. Specify the direction that the automobile should move in order to generate the maximum motional emf in the antenna, with the top of the antenna positive relative to the bottom. 1. Unable to determine. 2. west 3. south 4. north 5. east 009
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Find the magnitude of this induced emf. Answer in units of V. Rotating Metal Bar 02 31:05, calculus, multiple choice, > 1 min, wording-variable. 010 A metal bar with length OA = L is rotating in a counter-clockwise manner about the point O with a constant angular velocity . There is a constant magnetic eld B directed out of the paper.
v
B
A
C +q
L
O
B
B
The direction of the magnetic force on the positive charge +q at a xed point C due to the magnetic eld, and the relationship between VO and VA are respectively given by 1. radially outward, VA > VO . 2. radially outward, VO > VA . 3. radially inward, VA > VO . 4. radially inward, VO > VA . 5. radially outward, VO = VA . 6. radially inward, VO = VA . 7. opposite to the direction of v , VO = VA . 8. in the direction of v , VO = VA .
Create assignment, 57112, Homework 13, Sep 01 at 11:29 am 9. in the plane, VO = VA . 10. out of the plane, VO = VA . 011 The length of the bar is 10 m and the magnitude of the magnetic eld is 9 T . The speed of the bar at point C is 33 m/s , and the length of OC = 4 m . Determine the magnitude of the potential dierence |VO VA | . 1. |VO VA | = 7425 V 2
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2. |VO VA | = 7425 V 1485 V 4 1485 5. |VO VA | = V 2 6. |VO VA | = 1485 V 7. |VO VA | = 3. |VO VA | = 14850 V
4. |VO VA | =
297 V 5 594 8. |VO VA | = V 5 1782 9. |VO VA | = V 5 1485 10. |VO VA | = V 14
Answers: 001: 002: 003: 004: 005: 006: 007: 008: 009: 010: 011: 0.0618265 V 57.6 N 115.2 W 0.00111111 V 0.004 V :-X 0.674192 V :-X 0.000457836 V :-X :-X