A workshop needs an electromagnet capable of holding iron pieces weighing up to
PHYSICS · Multi-part · CBSE · Physics · Magnetic Effects of Electric Current · Magnetic Effects of Electric Current
Problem
A workshop needs an electromagnet capable of holding iron pieces weighing up to 10kg. The available d.c. supply provides a steady current of 4A. The technician decides to construct a long solenoid around a cylindrical soft iron core.
(a) Outline the steps you would follow to design such an electromagnet, mentioning how you would decide on (i) the number of turns per unit length, (ii) the choice of core material, and (iii) the length of the solenoid relative to its diameter.
(b) Explain, with reasons, how each of the following changes would affect the holding capacity of the electromagnet:
(i) increasing the current to 6A,
(ii) replacing the soft iron core with a steel core,
(iii) doubling the number of turns while keeping the length the same.
(c) The electromagnet is required to release the iron pieces quickly when the current is switched off. Discuss two design considerations that help achieve rapid magnetisation and demagnetisation of the core.