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# Electromagnet and permanent magnet

Tutormate > CBSE Syllabus-Class 10th Physics > Electromagnet and permanent magnet

## 04 Magnetic

#### ELECTROMAGNET

• An electromagnet works on the magnetic effect of current.
• An electromagnet is a magnet consisting of a long coil of insulated copper wire wrapped around a soft iron core that is magnetized only when electric current is passed through the coil.

#### FACTORS AFFECTING THE STRENGTH OF AN ELECTROMAGNET

The strength of an electromagnet depends on:

(i) The number of turns in the coil. If we increase the number of turns in the coil, the strength of electromagnet increases.

(ii) The current flowing in the coil. If the current in the coil is increased, the strength of electromagnet increases.

(iii) The length of air gap between its poles.

#### DIFFERENCES BETWEEN A BAR MAGNET (OR PERMANENT MAGNET) AND AN ELECTROMAGNET

 Bar magnet (or Permanent magnet) Electromagnet 1. The bar magnet is a permanent magnet. 1. An electromagnet is a temporary magnet. Its magnetism is only for the duration of current passing through it. So, the magnetism of an electromagnet can be switched on or switched off as desired. 2. A permanent magnet produces a comparatively weak force of attraction. 2. An electromagnet can produce very strong magnetic force. 3. The strength of a permanent magnet cannot be changed. 3. The strength of an electromagnet can be changed by changing the number of turns in its coil or by changing the current passing through it. 4. The (north-south) polarity of a permanent magnet is fixed and cannot be changed. 4. The polarity of an electromagnet can be changed by changing the direction of current in its coil.