Question

Electromagnets are used in which of the following devices?
A) Speaker
B) Motor
C) Generator
D) All of the above

Answer 1

Hint:An electromagnet is the type of magnet in which the electric current is responsible for the generation of the magnetic field and it is basically a wire which is turned into a coil. In other words, when an electric current is allowed to pass through the coil, the metal becomes magnetic.

Complete step by step answer
Step 1: Mention the working principle of the electromagnet to get a better understanding of its applications.
Electric current through a conductor will produce a magnetic field which is perpendicular to the direction of the flow of current in the conductor. An electromagnet can be considered to operate on electricity. When current is passed through an electromagnet, a magnetic field will be generated. The strength of this field can be increased by increasing the current through the coil. The generation of the magnetic field indicates the magnetization of the material. To demagnetize the material we simply have to reverse the direction of the current flow. So by controlling the amount and direction of the current, we can control the amount and direction of the generated magnetic field of the electromagnet.

Step 2: Try to describe the working of a speaker, a motor and a generator.
A speaker has an iron coil in it which is placed in front of a permanent magnet. When the speaker is hooked up to a stereo, electrical signals will be fed through the speaker cables into the coil and thus turn it into an electromagnet. As electricity flows through the electromagnet, it will attract or repel the permanent magnet which causes the diaphragm of the speaker to vibrate and produce sound.
A motor also has a coil and when electric current flows through the coil, a magnetic field gets generated. This field will then cause the motor to spin or move.
A generator consists of a coil of wire placed between two magnets of opposite poles. So as the coil is spun between these two magnets, an electric current gets generated which can then be used to power other electronic devices.
So all the three devices – speaker, motor and generator use electromagnets for their working.

Hence the correct option is D.

Note:A speaker converts electrical energy into sound energy. An electric motor converts electrical energy into mechanical energy while an electric generator converts mechanical energy into electrical energy. The electric generator works on the principle of induction where movement is used to create electricity.