A 20-cm-long, zero-resistance wire is pulled outward, on zero-resistance rails,

Question

A 20-cm-long, zero-resistance wire is pulled outward, on zero-resistance rails, at a steady speed of 1.0m/s in a 0.10T magnetic field (See the figure). On the opposite side, a 1.0? carbon resistor completes the circuit by connecting the two rails. The mass of the resistor is 73mg .(Figure 1)

Part A

What is the induced current in the circuit?

Part B

How much force is needed to pull the wire at this speed?

Part C

How much does the temperature of the carbon increase if the wire is pulled for 10 s? The specific heat of carbon is 710J/kg??C.

Explanation / Answer

acc is 0 so F=BIL
also current I is BVL/R
I=.020A
F=0.1*0.020*0.20 =4*10^-4N
power= I^2*R
=4.00*10^-4J/sec
so for 10 sec 4*10^-3J
energy=mass*s*change in temp
=73*10^-3*710*T
T comes out to be 7.7*10^-5

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