A battery has an e.m.f. of 12V and an internal
resistance of 4. The power dissipated in a 20
resistor connected across its terminals
will be
The answer is :- 4
Total circuit resistance is 24. Therefore, by Ohm's law, the circuit
current will be. I= V / R = 12/24 = 0.5A. The voltage on the
24
resistor will be V = I x R = 0.5 x 20 =
10V. The power dissipated by the resistor, P = V x I = 10 x 0.5
= 5W. This can also be calculated using the equation P =
I2 x R = 0.52 x 20 = 5W
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