Two resistances 25 Ohm and 15 Ohm are connected in parallel and connected to a source with an EMF of 15 V.

| March 7, 2021 | education

Two resistances 25 Ohm and 15 Ohm are connected in parallel and connected to a source with an EMF of 15 V. The current in the common circuit is 1.5 A. Find the short-circuit current of this source.

R1 = 25 ohms.

R2 = 15 ohms.

I = 1.5 A.

EMF = 15 V.

Ikor -?

A short circuit is a state of the circuit in which there is no external resistance R = 0, the current reaches the maximum possible value.

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

R + r = EMF / I.

r = EMF / I – R.

In case of short circuit R = 0, Icor = EMF / r.

With parallel connection of conductors, the total resistance of the circuit R is expressed by the formula: R = R1 * R2 / (R1 + R2).

R = 25 ohms * 15 ohms / (25 ohms + 15 ohms) = 9.375 ohms.

r = 15 V / 1.5 A – 9.375 Ohm = 0.625 Ohm.

Icor = 15 V / 0.635 Ohm = 23.6 A.

Answer: with a short circuit, the current strength is Icor = 23.6 A.



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