Question

In the following circuit a 10 m long potentiometer wire with resistance 1.2 ohm/m, a resistance R₁ and an accumulator of emf 2 V are connected in series. When the emf of thermocouple is 2.4 mV then the deflection in galvanometer is zero. The current supplied by the accumulator will be

• A. $4\times {10}^{-4}A$
• B. $8\times {10}^{-4}A$
• C. $4\times {10}^{-3}A$
• D. $8\times {10}^{-3}A$

Answer 1

The correct option is A $4\times {10}^{-4}A$

$E=xl=i\rho l$ $\therefore i=\frac{E}{\rho l}=\frac{E}{\rho l}=\frac{2.4\times {10}^{-3}}{1.2\times 5}=4\times {10}^{-4}A$