. 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.

 

Best Answer

Answer: (i) In the First Case:

Potential difference, V = 6 V

And, Net Resistance, R= 1 + 2 = 3  (Resistors are connected in series)

were

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

were

(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

were

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

 

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