A. 1.
Phy 122 - Assignment 6
2.
B. 1.
E
= -L ( I/ t). Leave out the minus because it asks for the magnitude.
L ( I/ t) = (.003 H)[(1.5 - .2)/(.2 s)] = .0195 V

2.
C.
D. 1.
E
= -L ( I/ t)
(-.096 V) = -L (1.20 A/s)

(Inductance, L, is always a positive number. So, when the question said 96.0 mV, it must have been giving just the size of the voltage without considering its polarity. I stuck in a minus to make L come out positive.)
L = .096/1.2 = .080 H, or 80 mH ans.
2.
E. 1. No – The battery would put a steady current through the primary, creating a constant magnetic field. By Faraday’s law, the magnetic field must be changing to induce an emf in the secondary coil.
2.

By the right hand rule, this field’s direction is out of the page, +z. (Wrap the direction of B .)
F = qvB sin = (1.602 x 10
-19
C)(3.50 x 10
5 m/s)(1.999 x 10
-5
T)(1)
= 1.12 x 10
-18
N
Direction:
B
The force is perpendicular to both
 v
and
, so it’s got to be either +x or –x. Choose between these with the right hand rule: Wrap your fingers around the x axis pointing from v toward B. Your thumb points in the direction of the force on a positive charge. That’s +x in this case. Since the charge is actually negative, it’s the other way.
Ans.: 1.12 x 10 -18 N in the -x direction.