An alternator initially supplies an rms voltage of at a frequency of to a fixed…
PHYSICS · Multi-part · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
An alternator initially supplies an rms voltage of 100V at a frequency of 50Hz to a fixed resistive load of 25Ω. A reduction in driving torque causes the rotational speed to fall so that the electrical frequency becomes 40Hz, while the magnetic field strength and all other parameters of the alternator remain unchanged.
(i) Determine the percentage reduction in the maximum induced emf and in the rms terminal voltage of the alternator.
(ii) Calculate the new rms current in the load and the new average power delivered to it.