Question 262: Current Electricity

Question

The length of a potentiometer wire is 1200 cm
and it carries a current of 60 mA. For a cell of
emf 5V and internal resistance of 20$$\Omega $$, the null
point on it is found to be a 1000 cm. The
resistance of whole wire is :

Accepted Answer

Let Resistance per unit length of potentiometer wire = $$\lambda $$
5 = $$\lambda $$ $$ 	imes $$ 1000 $$ 	imes $$ 60 $$ 	imes $$ 10
-3
$$ \Rightarrow $$ $$\lambda $$ = $${5 \over {60}}$$
Resistance of potentiometer wire = 1200 $$ 	imes $$ $${5 \over {60}}$$ = 100 $$\Omega $$

Answer

80$$\Omega $$

Answer

60$$\Omega $$

Answer

120$$\Omega $$

Answer

100$$\Omega $$

Current Electricity

The length of a potentiometer wire is 1200 cm and it carries a current of 60 mA. For a cell of emf 5V and internal resistance of 20$\Omega $, the null point on it is found to be a 1000 cm. The resistance of whole wire is :

Choose the correct answer: