Question 305: Current Electricity

Question

In the given figure, a battery of emf E is connected across a conductor PQ of length 'l' and different area of cross-sections having radii r
1
and r
2
(r
2
< r
1
).
Choose the correct option as one moves from P to Q :
![](https://imagex.cdn.examgoal.net/1ks0l84id/8cabff5f-ef89-49ed-893d-dfec7cdd411d/e498b760-f6d6-11eb-b70a-fb95473082c0/file-1ks0l84ie.jpg)

Accepted Answer

Current is constant in conductor
i = constant
Resistance of element $dR = {{ho dx} \over {\pi {r^2}}}$
$dV = idR = {{iho dx} \over {\pi {r^2}}}$
$E = {{dV} \over {dx}} = {{iho } \over {\pi {r^2}}}$
& ${V_d} = {{eE	au } \over m}$
$	herefore$ ${V_d} \propto E$
$ 	o E \propto {1 \over {{r^2}}}$
if r decreases, E will increase : V
d
will increase
![](https://imagex.cdn.examgoal.net/1ks0l90cf/bfb41207-2628-4298-ac98-cf12a9e4c73a/fd3008f0-f6d6-11eb-b326-31a7780220e7/file-1ks0l90cg.png)

Answer

Drift velocity of electron increases.

Answer

Electric field decreases.

Answer

Electron current decreases.

Answer

All of these

Current Electricity

In the given figure, a battery of emf E is connected across a conductor PQ of length 'l' and different area of cross-sections having radii r 1 and r 2 (r 2 < r 1 ). Choose the correct option as one moves from P to Q :

Choose the correct answer: