Question 364: Current Electricity

Question

An ideal battery of 4 V and resistance R are connected in series in the primary circuit of a potentiometer of length 1 m and  esistance 5 $\Omega $. The value of R, to give a potential difference of 5 mV across 10 cm of potentiometer wire, is :

Accepted Answer

Let current flowing in the wire is i.
$ 	herefore $  i = $\left( {{4 \over {R + 5}}} ight)A$
If resistance of 10 m length of wire is x
then x = 0.5 $\Omega $ = 5 $ 	imes $ ${{0.1} \over 1}$ $\Omega $
$ 	herefore $   $\Delta $V = P.d. on wire = i. x
5 $ 	imes $ 10
$-$3
= $\left( {{4 \over {R + 5}}} ight)$.(0.5)
$ 	herefore $   ${{4 \over {R + 5}}}$ = 10
$-$2
or   R + 5 = 400 $\Omega $
$ 	herefore $   R = 395 $\Omega $

Answer

480 $\Omega $

Answer

495 $\Omega $

Answer

490 $\Omega $

Answer

395 $\Omega $

Current Electricity

An ideal battery of 4 V and resistance R are connected in series in the primary circuit of a potentiometer of length 1 m and esistance 5 \Omega . The value of R, to give a potential difference of 5 mV across 10 cm of potentiometer wire, is :

Choose the correct answer: