Question 663: Current Electricity

Question

A potentiometer wire has length 4 m and resistance 8 $$\Omega $$. The resistance that must be connected in series with the wire and an accumulator of e.m.f. 2 V, so as to get a potential gradient 1 mV per cm on the wire is

Accepted Answer

Total potential difference across potentiometer wire
= 10
Ã¢ÂÂ3
ÃÂ 400 volt = 0.4 volt
potential gradient = $${{1mv} \over {cm}}$$
$$ = {10^{ - 3}}v/cm = {10^{ - 1}}{v \over m}$$
Let resistance of R$$\Omega $$ connected in series.
$$ 	herefore $$ $${2 \over {R + 8}} = {{{{10}^{ - 1}} 	imes 4} \over 8} = {1 \over {20}}$$
$$ \Rightarrow $$ R + 8 = 40  or, R = 32 $$\Omega $$

Answer

44 $$\Omega $$

Answer

48 $$\Omega $$

Answer

32 $$\Omega $$

Answer

40 $$\Omega $$

Current Electricity

A potentiometer wire has length 4 m and resistance 8 $\Omega $. The resistance that must be connected in series with the wire and an accumulator of e.m.f. 2 V, so as to get a potential gradient 1 mV per cm on the wire is

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