Compare the power used in the 2 Ω resistor in each of the following circuits:
(i) a 6 V battery in series with 1 Ω and 2 Ω resistors, and (ii) a 4 V battery in parallel
with 12 Ω and 2 Ω resistors.

NCERT Question 14 Compare the power used in the 2 Ω resistor in each of the following circuits: (i) a 6 V battery in series with 1 Ω and 2 Ω resistors, and
Given
Potential Difference = V = 6 V
R1 = 1 Ω
R2 = 2 Ω
We know that in series combination,
the current through each individual resistors is same as the current through circuit.
Finding equivalent resistance
In a series combination
the equivalent resistance is given by
RS = R1 + R2
RS = 1 + 2
RS = 3 Ω
Finding current
By Ohm’s law,
V = I × RS
∴ I = 𝑉/𝑅_𝑆
I = 6/3
I = 2 A
Finding Power in 2 Ω resistor
We know that
Power = I2 R
P = (2)2 (2)
P = 4 × 2
P = 8 W
∴ Power of 2 Ω resistors is 8W
NCERT Question 14 Compare the power used in the 2 Ω resistor in each of the following circuits: (ii) a 4 V battery in parallel with 12 Ω and 2 Ω resistors.
Given
Potential Difference = V = 4 V
R1 = 12 Ω
R2 = 2 Ω
We know that in parallel combination,
the potential difference across each resistors is same as the total potential difference in the circuit
Hence, potential difference across 2 Ω resistor is 4 V
Finding Power in 2 Ω resistor
We know that
P = 𝑉^2/𝑅
P = (4)^2/2
P = 16/2
P = 8 W
Power of 2 Ω resistor is 8 W

CA Maninder Singh is a Chartered Accountant for the past 11 years and a teacher from the past 11 years. He teaches Science, Accounts and English at Teachoo