A circuit consists of two fixed resistors

PHYSICS · Subjective · CBSE · Physics · Current Electricity · Current Electricity

Problem

R_{1}=5\,\Omega

R_{2}=10\,\Omega

and a temperature-dependent resistor

R_{T}

connected in series to a

12\,\text{V}

ideal source. The resistance of

R_{T}

20^{\circ}\text{C}

2.0\,\Omega

, and its temperature coefficient of resistance is

\alpha = 4.0\times 10^{-3}\,{}^{\circ}\text{C}^{-1}

. (a) Write the expression for the resistance of

R_{T}

at a temperature

T

in terms of its value at

20^{\circ}\text{C}

. (b) Calculate the total circuit current at

20^{\circ}\text{C}

. (c) The circuit is now heated uniformly to

60^{\circ}\text{C}

. Determine the new value of

R_{T}

and hence the current in the circuit. (d) Find the percentage change in the power dissipated by

R_{1}

due to the rise in temperature.