In the Fig above, Current I passes through the combination, if the power dissipated in the 5 ohm resistor is 40W, then the power dissipated in the 10 ohm resistor is
Attached Figure / Diagram
A
10W
B
20W
C
40W
D
80W
E
100W
Verified Correct Answer: B.
Physical Principles & Numerical Solution
Since the resistors are in parallel, the p.d across them is the same,
P = VI but I = \(\frac{ V}{R}\)
P = \(\frac{ V^2}{R}\) = power dissipated by 5\Omega resistor,
40 = \(\frac{ V^2}{5}\)
\(V^2\) = 200V.
Power dissipated by the 10\Omega resistor,
P = \(\frac{ V^2}{R}\) = \(\frac{200}{10}\)
P = 20W.
Source: Myschool Past Questions Archive (Record #41647)