What amount of heat will be released in 30 minutes by a 20 Ohm wire spiral with a current of 5 A?

t = 30 min = 1800 s.

R = 20 ohms.

I = 5 A.

Q -?

The amount of heat Q that is released in a conductor with a current is determined by the Joule-Lenz law: Q = I * U * t, where I is the current in the conductor, U is the voltage at the ends of the conductor, t is the time the current passes through the conductor.

We express the voltage U from Ohm’s law for a section of the circuit: U = I * R, where R is the resistance of the conductor.

Q = I ^ 2 * R * t.

Q = (5 A) ^ 2 * 20 Ohm * 1800 s = 900000 J.

Answer: in a conductor with a current, heat energy Q = 900000 J.



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