A battery with an EMF of 6 V and an internal resistance of 0.2 ohms feeds an external circuit with a resistance of 2.8 ohms

| May 22, 2021 | education

A battery with an EMF of 6 V and an internal resistance of 0.2 ohms feeds an external circuit with a resistance of 2.8 ohms. How much heat will be released in the external circuit in 5 minutes?

EMF = 6 V.

r = 0.2 ohm.

R = 2.8 ohms.

t = 5 min = 300 s.

Q -?

The amount of heat Q that is released when current passes through the conductor is determined by the Joule-Lenz law: Q = I2 * R * t, where I is the current in the conductor, R is the resistance of the conductor, t is the time during which the current flows.

We find the current strength in the external circuit 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 internal resistance of the current source.

I = 6 V / (2.8 ohms + 0.2 ohms) = 2 A.

Q = (2 A) 2 * 2.8 Ohm * 300 s = 3360 J.

Answer: heat energy is released in the conductor Q = 3360 J.



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