Question

Compare the power used in 2 ohm resistor in each of the following circuits

a)6 volt battery in series with 1 ohm and 2 ohm resistors

And

b)4 volt battery in parallel with 12 ohm and 2 ohm resistors

Answer 1

(a) In series circuit, the same current passes through the resistors, so you can take it to be constant. Hence , the power generated is;
P = (I^2)×R
R = (1+2) ohm = 3ohm
I = V/R
= 6v/ 3 ohm
= 2 A
power transmitted through 2 ohm;
P = (I^2) × R
= 4 × 2
=8 watts
(b) Potential difference is constant in a parallel circuit. Therefore the power transmitted through 2ohm resistance can be directly calculated as;
​​​​​​ P = (V^2)/R
P = (6^2)/2
= 18 watts