Current Electricity Charging Discharging Of Capacitors Question 526
Two wires A and B of same material and mass have their lengths in the ratio 1 : 2. On connecting them to the same source, the rate of heat dissipation in B is found to be 5W. The rate of heat dissipation in A is 20W.
[AMU (Engg.) 2000]
Options:
10W
5W
20W
D) None of these
Show Answer
Answer:
Correct Answer: C
Solution:
$ \frac{H}{t}=P=\frac{V^{2}}{R}\Rightarrow P\propto \frac{1}{R} $ also $ R\propto \frac{l}{A}\propto \frac{l}{A} $
Therefore $ R\propto \frac{l^{2}}{m} $
Therefore $ R\propto l^{2} $ (for same mass) So $ \frac{P _{A}}{P _{B}}=\frac{l _{A}^{2}}{l _{B}^{2}}=\frac{1}{4}\Rightarrow P _{A}=5,W $
BETA
