# In a rheostat, a resistance of 200 ohms flows a current of 200 mA. determine the work of electric current in 1 minute

Given:

R = 200 Ohm – rheostat resistance;

I = 200 mA = 0.2 Ampere – current flowing in the rheostat;

t = 1 minute = 60 seconds – time span.

It is required to determine A (Joule) – the work of an electric current for a time interval t.

Let’s find the voltage of the electrical circuit (according to Ohm’s law):

U = I * R.

Then the current power will be equal to:

W = U * I = I * R * I = I ^ 2 * R.

The work of the electric current will be equal to:

A = W * t = I ^ 2 * R * t;

A = 0.2 ^ 2 * 200 * 60 = 0.04 * 200 * 60 = 8 * 60 = 480 Joules (0.48 kJ).

Answer: in 1 minute, the electric current passing through the rheostat performed work equal to 480 Joules.

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