Current Electricity 3 Question 11
10. A wire of length and 3 identical cells of negligible internal resistances are connected in series. Due to the current, the temperature of the wire is raised by in a time . A number of similar cells is now connected in series with a wire of the same material and cross-section but of length . The temperature of the wire is raised by the same amount in the same time. The value of is
(a) 4
(b) 6
(c) 8
(d) 9
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Solution:
- In the first case
When length of the wire is doubled, resistance and mass both are doubled.
Therefore, in the second case,
Dividing Eq. (ii) by (i), we get