As shown in the figure, a potentiometer wire of resistance $20 \, \Omega$ and length $300 \, ext{cm}$ is connected with resistance box (R.B.) and a standard cell of emf $4 \, V$. For a resistance '$R$' of resistance box introduced into the circuit, the null point for a cell of $20 \, mV$ is…

Question

As shown in the figure, a potentiometer wire of resistance $20 \, \Omega$ and length $300 \, 	ext{cm}$ is connected with resistance box (R.B.) and a standard cell of emf $4 \, V$. For a resistance '$R$' of resistance box introduced into the circuit, the null point for a cell of $20 \, mV$ is found to be $60 \, 	ext{cm}$. The value of '$R$ is_____ $\Omega$.

Aicharya · Accepted Answer

Given here, l = 300 &#160; cm , R w = 20 &#160; &#937; and &#949; = 4 &#160; V . Using the relation, E 2 = l 1 l 2 E 1 , we have E = A C A B V A - V B &#8756; 20 &#215; 10 - 3 = 60 300 &#215; 4 &#215; 20 R + 20 &#8658; 5 &#215; 10 - 3 = 4 R + 20 &#8756; R = 780 &#160; &#937;

As shown in the figure, a potentiometer wire of resistance $20 \, \Omega$ and length $300 \, \text{cm}$ is…

Solution