Q.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 (ii) a 4 V battery in parallel with 12 Ω and 2 Ω resistors.
(i) Potential difference (V) = 6 V
Here 1 Ω and 2 Ω resistors are connected in series.
∴ equivalent resistance of the circuit (R) = 1 + 2 = 3 Ω
According to Ohm’s law
V = IR
the current through the circuit (I)=2A
Now the power used in the 2 Ω resistor
we know that Power = I2R
(ii) Potential difference, V = 4 V
12 Ω and 2 Ω resistors are connected in parallel. The voltage across each component of a parallel circuit remains the same. Hence, the voltage across 2 Ω resistor will be 4 V. Power consumed by 2 Ω resistor is given by
∴ the power used by 2 Ω resistor is 8 W.