. Compare the power used in the 2 resistor in each of the following circuits
(i) a 6 V battery in series with 1 and 2 a resistors.
(ii) a 4 V battery in parallel with 12 and 2 resistors.
Answer: (i) In the First Case:
Potential difference, V = 6 V
And, Net Resistance, R= 1 + 2 = 3 (Resistors are connected in series)
Thus, the current flowing in the circuit containing 1 and 2 resistors in series is 2 A. In a series circuit, the same current flows throughout the circuit. So, the current flowing through the 2 resistor is also 2A. Now, we know that the current (in 2 resistor) is 2 A and its resistance is 2 .
Now, Power used in 2 resistor is given as
(ii) In the Second Case:
Here, 4 V battery is attached across the parallel combination of 12 and 2 resistors, so the potential difference across the 2 resistor will also be 4 V . Because in parallel connection
Voltage is same.
Now, Potential difference, V= 4 V
And Resistance, R = 2
Thus, the power used in the 2 resistor in the second case is also 8W.
From both the cases we can say that the 2 resistor uses equal power in both the circuits