Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 11
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A resistor held in running water carries electric current. Treat the resistor as the system - Physics

Answer in Brief

A resistor held in running water carries electric current. Treat the resistor as the system (a) Does heat flow into the resistor? (b) Is there a flow of heat into the water? (c) Is any work done? (d) Assuming the state of resistance to remain unchanged, apply the first law of thermodynamics to this process.

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Solution

(a) Heat is generated into the resistor due to the passage of electric current. In the usual notation, heat generated = I2Rt.

(b) Yes. Water receives heat from the resistor.

(c) l2Rt = MCΔT + PΔV
(Q) (Δ U) (W)

Here, I = current through the resistor, R = resistance of the resistor, t = time for which the current is passed through the resistor, M = mass of the water, S = specific heat of water, T = rise in the temperature of water, P = pressure against which the work is done by the water, Δ U = increase in the volume of the water.

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APPEARS IN

Balbharati Physics 12th Standard HSC Maharashtra State Board
Chapter 4 Thermodynamics
Exercises | Q 3.2 | Page 107
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