Question

Electromagnets are used in
A. Electric bells
B. Telephones
C. Dynamo
D. All of these

Answer 1

Hint:Electromagnet consists of wire wound into a coil when an electric current is passed through the coil then it produces a magnetic field and this magnetic field disappears when the current flowing through is turned off. It is widely used in electrical devices.

Complete answer:
An electromagnet is a temporary magnet which behaves like a magnet when electric current is passed through the insulated copper wire because when electric current pasees throuht the coil it produces a magnetic field around it. At the same time it loses magnetic property when the current stops flowing across it.

It is made up of a soft iron piece known as core with an insulating wire wound around it.Electromagnets are used in telephones. It is connected in the earpiece of a telephone ,when you speak through the telephone your sound will be converted into electric current by the mouthpiece of the telephone.An electromagnet is used in Electric bell.

An electromagnet is fitted in such a way that when the switch is turned on,it creates a magnetic field due to which a nearby magnetic hamer would be attracted to it and strike it thereby creating the sound of the bell.An electromagnet is used in dynamo. The armantire plays the role of an electromagnet. It is made of coiled copper windings which rotate inside the magnetic field made by the stator.

Therefore the correct option is D.

Note:Remember that electromagnetism is a branch of physics which is one of the four fundamental forces and exhibits electromagnetic fields such as magnetic fields, electric fields, ang light. It is measured with the help of Fleming's left hand rule.