This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: terry (ect328) homework 25 Turner (59130) 1 This printout should have 11 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points In the arrangement shown in the figure, the resistor is R and a B magnetic field is directed out of the paper. The separation between the rails is . Neglect the mass m of the bar. Assume the bar and rails have negligible resistance and friction. An applied force moves the bar to the left at a constant speed of v . m v R B B a z What is the relationship between the elec tric potential at the ends of the resistor ( z or a ) while the bar is moving on the right side of the resistor (towards the resistor) and mov ing on the left side of the resistor (after the bar moves past the resistor)? 1. V a > V z (right) and V z > V a (left) 2. V z > V a (right) and V z > V a (left) 3. V a > V z (right) and V a > V z (left) correct 4. V z > V a (right) and V a > V z (left) 5. V z = V a (right) and V z = V a Explanation: As the bar moves toward the resistor, the area of the current loop decreases, so the induced B ind is upward with I ind counter clockwire from above. Lenzs law dictates that before moving past the resistor, current flows from a to z , so a is at a higher potential. After going past the resistor, Lenzs law dictates that the induced B ind is now down ward. This requires the current to reverse its ro tational direction to be clockwise from above. However, the direction a to z (through the resistor R ) also reverses its rotational direc tion. The emf across the bar does not change sign; i.e. , the current through the resistor R remains in the same direction. 002 10.0 points A rectangular coil of 50 turns, 0 . 26 m by . 2 m, is rotated at 141 rad / s in a magnetic field so that the axis of rotation is perpendicu lar to the direction of the field. The maximum emf induced in the coil is 0 . 3 V. What is the magnitude of the field?...
View
Full
Document
This note was uploaded on 11/28/2010 for the course PHY 56705 taught by Professor Turner during the Spring '10 term at University of Texas at Austin.
 Spring '10
 Turner

Click to edit the document details