A closed circuit consists of a current source with an EMF e = 16 V with an internal resistance r = 1 Ohm and a load.

| September 24, 2021 | education

A closed circuit consists of a current source with an EMF e = 16 V with an internal resistance r = 1 Ohm and a load. Determine the resistance of the load if the power is released on it P = 16 W.

EMF = 16 V.

r = 1 ohm.

P = 16 W.

R -?

Let us express the power of the external load P according to the Joule-Lenz formula: P = EMF * I, where I is the current in the external circuit, EMF is the electromotive force of the current source.

According to Ohm’s law for a closed loop, the current in the circuit I is directly proportional to the electromotive force of the EMF current source and is inversely proportional to the sum of the external resistance R and the internal resistance of the current source r: I = EMF / (R + r).

The formula for the load power P will take the form: P = EMF ^ 2 / (R + r).

R + r = EMF ^ 2 / R.

R = EMF ^ 2 / P – r.

R = (16V) ^ 2 / 16W – 1 ohm = 15 ohm.

Answer: the resistance of the external load is R = 15 ohms.



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