What is the external resistance of the circuit if the EMF of the power source is 2v, the internal resistance is 1.5 ohms

| August 16, 2021 | education

What is the external resistance of the circuit if the EMF of the power source is 2v, the internal resistance is 1.5 ohms and the current in the circuit is 0.5A? what is the voltage drop in the circuit?

EMF = 2 V.

r = 1.5 ohms.

I = 0.5 A.

R -?

U -?

Let us write Ohm’s law for a closed circuit: 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 = EMF / I – r.

R = 2 V / 0.5 A – 1.5 Ohm = 2.5 Ohm.

The voltage drop across the resistance U is found according to Ohm’s law for a section of the circuit: U = I * R.

U = 0.5 A * 2.5 Ohm = 1.25 V.

Answer: the external resistance of the circuit is R = 2.5 Ohm, the voltage drop across the resistance is U = 1.25 V.



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