A current source with an EMF of 25V and an internal resistance of 3 Ohm

| April 26, 2021 | education

A current source with an EMF of 25V and an internal resistance of 3 Ohm is closed to an external resistance of 15 Ohm. Determine the thermal power released in the external circuit.

EMF = 25 V.

r = 3 ohms.

R = 15 ohms.

N -?

The thermal power of the current N in the external circuit is determined by the formula: N = I * U, where I is the current in the external circuit, U is the voltage in the external circuit.

We find the current strength I according to Ohm’s law for a closed circuit: I = EMF / (R + r), where EMF is the electromotive force of the current source, R is the external resistance, r is the resistance of the current source.

I = 25 V / (15 Ohm + 3 Ohm) = 1.4 A.

We express the voltage in the external circuit U about Ohm’s law for a section of the circuit: U = I * R.

U = 1.4 A * 15 Ohm = 21 V.

N = 1.4 A * 21 B = 29.4 W.

Answer: thermal power N = 29.4 W is released in the external circuit.



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