Current Electricity 4 Question 24
24. Statement I In a meter bridge experiment, null point for an unknown resistance is measured. Now, the unknown resistance is put inside an enclosure maintained at a higher temperature. The null point can be obtained at the same point as before by decreasing the value of the standard resistance.
Statement II Resistance of a metal increases with increase in temperature.
$(2008,3$ M)
Objective Questions II
(One or more correct option)
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Solution:
- With increase in temperature, the value of unknown resistance will increase.
In balanced Wheat stone bridge condition,
$$ \frac{R}{X}=\frac{l _1}{l _2} $$
Here, $R=$ value of standard resistance.
$$ X=\text { value of unknown resistance. } $$
To take null point at same point
or $\frac{l _1}{l _2}$ to remain unchanged, $\frac{R}{X}$ should also remain unchanged.
Therefore, if $X$ is increasing $R$, should also increase.
$\therefore$ Correct option is $(d)$.
