Question

In an electrical circuit, two resistors of 2 Ω and 4 Ω respectively are connected in series to a 6 V battery. The heat dissipated by the 4 Ω resistor in 5 s will be 

(a) 5 J

(b) 10 J 

(c) 20 J 

(d) 30 J

Answer 1

The answer is (c) 20 J

Equivalent resistance of the circuit is R = 4+2 = 6Ω 

current, I= (V/R)

 6/6 = 1A 

the heat dissipated by 4 ohm resistor is, 

H = IRt 

= 20J