JEE Advance - Physics (2008 - Paper 1 Offline - No. 11)
STATEMENT - 1
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.
and
STATEMENT - 2
Resistance of a metal increases with increase in temperature.
Explanation
When the temperature of a metal increases, its resistance will increase.
Therefore statement-2 is correct.
For meter bridge, when null point N is obtained, we get
$${X \over l} = {R \over {100 - l}}$$
When the unknown resistance is put inside an enclosure, maintained at a high temperature, then X increases. To maintain the ratio of null point, $$l$$ should also increase. But if we want to keep the null point at the initial position (i.e., if we want to change the value of $$l$$) to maintain the ratio, R should be increased.
Therefore, statement - 1 is false.
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