Question 454: Current Electricity

Question

A potentiometer wire of length 10 m and resistance 20 $$\Omega$$ is connected in series with a 25 V battery and an external resistance 30 $$\Omega$$. A cell of emf E in secondary circuit is balanced by 250 cm long potentiometer wire. The value of E (in volt) is $${x \over {10}}$$. The value of x is __________.

Accepted Answer

$$	herefore$$ $$E = I 	imes \left( {{{20} \over 4}} ight) = {{25} \over {(30 + 20)}} 	imes \left( {{{20} \over 4}} ight)$$
$$ = {1 \over 2} 	imes 5 = 2.5$$ volts
$$ = {{25} \over {10}}$$ volts

Current Electricity

Choose the correct answer: