Question:

A coil is placed in a time varying magnetic field. If the number of turns in the coil were to be halved and the radius of wire doubled, the electrical power dissipated due to the current induced in the coil would be: (Assume the coil to be short circuited.)

Updated On: Sep 24, 2024
  • Halved
  • Quadrupled
  • The same
  • Doubled
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The Correct Option is D

Solution and Explanation

As number of turns are halved so length of wire is halved, and radius is doubled, then area will be 4 times the previous one if previous resistance is R then new resistance is R/8 and if previous emf is E then new emf will be E/2 so
Pi \(\frac{E^2}{R}\)
Pf\(\frac{(E/2)^2}{R/8} =\frac{2E^2}{R}=2P_i\)
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Concepts Used:

Electric Power

Power is defined as the rate of doing work. Electric power is the rate at which electrical energy is transferred through an electric circuit, i.e. the rate of transfer of electricity. The symbol for Electric Power is ‘P’. SI unit of electric power is Watt. 

Electric Power Formula

P = VI 

From Ohm's Law, V = IR

Hence, Power can also be expressed as P = I2R