A 20-cm-long, zero-resistance slide wire moves outward, onzero-resistance rails,

Question

A 20-cm-long, zero-resistance slide wire moves outward, onzero-resistance rails, at a steady speed of 10 m/s in a 0.11 Tmagnetic field. On the opposite side, a 0.8 carbon resistorcompletes the circuit by connecting the two rails. The mass of theresistor is 50 mg. (a) What is the induced current in the circuit?
1 A

(b) How much force is needed to pull the wire at this speed?
2 N

(c) If the wire is pulled for 10 s, what is the temperatureincrease of the carbon? The specific heat of carbon is 710 J/kg· C°.
3°C I can't figure out (c), number 3.. Any help is lifesaver,thanks!

Explanation / Answer

c) We know that            Q= msT     Power is P = Q/t          But P = I2/R So I2/R = (ms T)/t The temperature increase of the carbon is               T = (t I2)/(ms) Here t = 10s          I = 0.275A          m =50*10-6kg          s = 710 J/kgoC Substitute the values for T.

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