Question

A permanent magnet is used in an electric bell. State whether the given statement is true or false.
A. True
B. False

Answer 1

Hint: Electric bells are mechanical or electronic bells that work on the principle of electromagnetism. That is when electric current flows through it produces a magnetic field due to which it starts ringing or produces sound.

Complete answer:
Permanent magnet is a device made from a magnetized material. After permanent magnets get magnetized it can retain the level of the magnetism for a long period of time. Then it loses its property.As the permanent magnetics loses its property after some time we cannot use it in electric bells because it needs continuous on off sequence and the reason behind this is continuous hammering and ringing so the bell.

Therefore for this kind of mechanism electromagnet is quite suitable because we can change the properties of electromagnet. As electromagnet are temporary magnets so we can easily change its properties.Hence an electric bell uses an electromagnet which is not a permanent magnet.So the given statement in the problem that a permanent magnet is used in an electric bell is false.

Therefore the correct option is B.

Note: Key point of this problem is that electric bells are made of up electromagnet which is a temporary magnet which makes the given statement false. We can change the property of a temporary magnet as it needs continuous on off sequence. Electric bells are used in: Telephones, fire alarm, school bells, doorbells, railroad crossings etc.