Question

How does an electromagnet work?

Hint:

Permanent magnets cannot be switched off, but electromagnets can — making them more useful in industries and machines.

Answer 1

Step 1: Introduction
An electromagnet is a type of temporary magnet which is formed by passing electric current through a coil wound around a soft iron core. Unlike permanent magnets, its magnetism can be turned on and off.
Step 2: Principle
It works on the principle of electromagnetism, discovered by Hans Christian Oersted. According to this principle, whenever current flows through a conductor, it produces a magnetic field around it.
Step 3: Construction
A long insulated copper wire is wound around a soft iron rod.
The ends of the wire are connected to a battery or power source.
When current flows, the iron core becomes magnetized and acts as a magnet.
Step 4: Working
When the circuit is switched ON, the current generates a strong magnetic field.
The soft iron core concentrates this magnetic field and becomes a powerful magnet.
When the circuit is switched OFF, the magnetism disappears almost completely.
Step 5: Factors Affecting Strength
Number of turns of the coil.
Magnitude of current.
Nature of the core material.
Step 6: Applications
Used in electric bells and buzzers.
Used in electric motors, relays, transformers.
Used in cranes to lift heavy iron objects in junkyards.
Final Answer:
An electromagnet works because electric current produces a magnetic field. The iron core enhances this field, making it strong enough for practical uses.