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 = \(\frac{(E/2)^2}{R/8} =\frac{2E^2}{R}=2P_i\)
As the answer key is changing students can challenge this question.
Physical quantity | SI Unit | ||
i | Electric current | a | Coulomb |
ii | Electric charge | b | Volt |
iii | Electric potential | c | Ampere |
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.
P = VI
From Ohm's Law, V = IR
Hence, Power can also be expressed as P = I2R