An infinite straight wire carries a current I that varies with time as shown abo
ID: 1309245 • Letter: A
Question
An infinite straight wire carries a current I that varies with time as shown above. It increases from 0 at t = 0 to a maximum value I1 = 4.5 A at t = t1 = 10 s, remains constant at this value until t = t2 when it decreases linearly to a value I4 = -4.5 A at t = t4 = 28 s, passing through zero at t = t3 = 21.5 s. A conducting loop with sides W = 29 cm and L = 56 cm is fixed in the x-y plane at a distance d = 32 cm from the wire as shown.
1)
What is the magnitude of the magnetic flux ? through the loop at time t = t1 = 10 s?
T-m2
2)
What is ?1, the induced emf in the loop at time t = 5 s? Define the emf to be positive if the induced current in the loop is clockwise and negative if the current is counter-clockwise.
V
3)
What is ?2, the induced emf in the loop at time t = 12 s? Define the emf to be positive if the induced current in the loop is clockwise and negative if the current is counter-clockwise.
V
4)
What is the direction of the induced current in the loop at time t = t3 = 21.5 seconds?
Clockwise
Counterclockwise
There is no induced current at t = t3
5)
What is ?4, the induced emf in the loop at time t = 24.75 s? Define the emf to be positive if the induced current in the loop is clockwise and negative if the current is counter-clockwise.
V
Explanation / Answer
1) Use the Biot-Savart for an infinitely long wire.
B = (