A generator consists of a coil with turns and area rotating in a uniform magnetic…
PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
A generator consists of a coil with N=300 turns and area 250cm2 rotating in a uniform magnetic field of 0.15T at an angular speed of 100rad s−1. The coil is connected to a purely resistive external load of resistance 50Ω.
(i) Derive an expression for the instantaneous emf e(t) generated by the coil.
(ii) Using Ohm’s law, obtain the expression for the instantaneous current i(t) in the external resistor.
(iii) Calculate the rms values of the emf and the current.
(iv) Determine the average power dissipated in the resistor and comment on how this power would change if the angular speed of the coil were doubled while all other parameters remained the same.