Question 79: Current Electricity

Question

In the balanced condition, the values of the resistances of the four arms of a Wheatstone bridge are shown in the figure below. The resistance R3 has temperature coefficient 0.0004$$^\circ$$C-1. If the temperature of R3 is increased by 100$$^\circ$$C, the voltage developed between S and T will be ________ volt.

Accepted Answer

$$R{'_3} = 300(1 + \alpha \Delta T) = 312\Omega $$
Now,
$${I_1} = {{50} \over {372}}$$ and $${I_2} = {{50} \over {600}}$$
$${V_S} - {V_T} = 312{I_1} - 500{I_2}$$
$$ = 41.94 - 41.67 = 0.27$$ V

Current Electricity

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