SP212/3321&5521
Chapter 30 - Worksheet #1
Question 1: A circular loop of initial radius Ri =0.150 m is placed in a uniform magnetic field
B=1.25 T directed into the page. The circle then expands to a final radius of Rf =0.450 m over a
period of 9.00 s. What is the average induced emf in the loop while it is expanding? Answer for
both the magnitude and direction of the induced emf.
Rf
×
×
×
×
×
×
×B=1.25 T
Ri
×
×
×
Question 2: A square loop of wire, 0.45 m on each side, lies in the plane of the page. A uniform
magnetic field points out of the page, and increases in magnitude from B=0 to B=3.50 T over
a time period of 25.0 s. Suppose that the resistance of the loop is 12.0 Ω. What is the average
induced current in the loop while the magnetic field is changing? Answer for both the magnitude
and direction of the induced current.
B is increasing
0.45 m
SP212/3321&5521
Chapter 30 - Worksheet #1
Question 3: A long wire is wrapped into a square loop 0.250 m on a side with N =75 turns. The
loop is placed in a magnetic field whose direction is out of the page and whose strength is given by
Bz (t) = 0.5t2 − 4t + 8, where Bz has units of tesla when t has units of seconds. (a) What is the
magnitude and direction of the induced emf in the loop at time t=1.5 s? (b) What is the magnitude
and direction of the induced emf in the loop at time t=5.5 s?
0.25 m
~
B