Question

Explain why thick blocks of metal are not used as the core of a transformer.
A) They generate current.
B) They generate emf.
C) They generate heat.
D) They generate induction.

Answer 1

Hint: The magnetic property of a material depends on the magnetic field it generates when placed in a magnetic field and on its dimensions. The core of the transformer must be made of a material such that the magnetic property of the core material does not get jeopardized or lost as it produces a magnetic field. A thick block of metal has low thermal resistance and hence it conducts heat easily.

Complete step by step answer:
Thick blocks of metal will produce a very large magnetic field. This large magnetic field will cause the block to heat up. The heat generated will be enormous and the temperature of the block will increase. The rise in temperature destroys the magnetic property of the metal block. But the core of the transformer requires it to constantly generate an alternating magnetic flux so that an emf is induced in the secondary coil of the transformer.
Thus, thick blocks of metal that generate large amounts of heat are never used as the core of the transformer. Hence the correct option is C.

Additional Information: The core of the transformer is made up of ferromagnetic materials. Ferromagnetic materials persist to have a magnetization even if the magnetic field is removed. The core of the transformer is usually made of soft iron as the heat generated by it will be minimum.

Note: When the thick block of metal loses its magnetic property, it, in fact, loses its ability to generate an induced emf. This is crucial as the whole working of the transformer is based on the principle of mutual induction. Mutual induction is the phenomenon by which a change in the current of one coil induces an emf in another coil.