Physics
In the circuit shown, lamps L1 and L2, are identical. The sliding contact at O moved towards Q, then which of the statements about the effect on the brightness in L2 is correct?
- Initially it has no light, then its brightness increases gradually and becomes equal to that of L1
- Initially it is same as that of L1, and finally become half as that of L1
- Initially it is half as that of L1 and finally becomes equal to that of L1.
- Initially it is half as that of L1 and finally becomes zero.
Current Electricity
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Answer
Initially it is half as that of L1 and finally becomes equal to that of L1.
Reason — Initially the pointer of sliding contact is at mid point of potential divider. So, the voltage across L2 is half as that across L1 and hence its brightness will also be half.
When the contact is moved to Q, the voltage across both lamps become equal and hence their brightness will also be equal.
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