Question

A short-circuited coil is placed in a time-varying magnetic field. Electrical power is dissipated due to the current induced in the coil. If the number of turns were to be quadrupled and the wire radius halved, the electrical power dissipated would be –
(a) halved
(b) the same
(c) doubled
(d) quadrupled

Answer 1

Electrical power is dissipated due to the current induced is given by p=V2/R.

Where V is the voltage of the coil

R is the resistance.

So a number of turns were to be quadrupled and the wire radius halved to the Voltage is V2 ( Where it becomes 16 times).

The resistance of the coil is 16 times, So R = ρL /A where ρ is the resistivity.

The length turns is quadrupled and the area of cross section becomes 4 times means one Fourth it will be halved.

So the given resistance, therefore, becomes 16 times.

Therefore the electrical power dissipated would be the same

Answer 2

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