Question

In an electrical circuit, two resistors of `2 Omega and 4 Omega` respectively are connected in series to a `6 V` battery. The heat dissipated by the `4 Omega` resistor in `5 s` will be :
A. 5 J
B. 10 J
C. 20 J
D. 30 J

Answer 1

Correct Answer - C
Current in the circuit, `I = (6 V)/(2 Omega + 4 Omega) = 1 A` (as `2 Omega and 4 Omega` resistors are in series)
Current through `4 Omega` resistor `= 1 A` (as both the resistors are in series)
Heat dissipated by the `4 Omega` resistor, `H = I^2 R t = (1 A)^2(4 Omega)(5 s) = 20 J`.