Concepts

Class 10
Chapter 13 Class 10 - Magnetic Effects of Electric Current

## What is Magnetic Field?

It is the region around the magnet where we are able to detect magnetic force of the magnet

Example

If a piece of iron is kept far away from the magnet, magnet is not able to attract it

But if we bring iron closer and closer,there would come a point when magnet is able to attract the iron

Magnetic field is the region in which the magnets show their properties.

## What are Magnetic Field Lines?

Magnetic Field lines are imaginary lines along which North Magnetic Pole would move.

In a bar magnet, the magnetic field lines look like

These are lines which shows direction of Magnetic Force and its strength

These are curved lines which start from North Pole of Magnet and Moves Towards South Pole

## Activity to see Magnetic Field Lines

Let's see how we can visually see Magnetic Field Lines

Let's perform an experiment

• Take a bar magnet and hundreds of iron filings
• Put the bar magnet on the table and spread the iron filings near the magnet,
• The iron filings are able to align themselves in a different curved lines
• These curved lines called Magnetic field lines

Check out the video below

## Important Properties of Magnetic Field and Magnetic Field Lines

Magnetic Field is a quantity that has both Magnitude as well as Direction

### Magnetic Field has Magnitude

Some Magnets have higher Strength than Other Magnets

This Magnetic Strength is shown by degree of closeness of field lines to each other

More crowded the field lines, more strong is the magnet

The magnetic fields line are closer to each other at poles, but are widely apart at other places.

Hence, magnetic field is strongest at the poles.

## Magnetic Field has Direction

The Magnetic Field lines are like closed curves

They emerge from North Pole and Merge to South Pole

Inside the magnet, field lines are opposite (From South Pole to North Pole)

### Field Lines do not cross each Other

All Field lines follow their separate path to reach from North Pole to South Pole

One field Line do not intersect or merge with Other Field Line

There is no point of intersection of 2 Field lines

If there was point of intersection, compass needle would point towards 2 directions.

Which means that the magnetic field has two different directions, which is not possible.

For more details, please check Why Magnetic Field Lines Do not Intersect

## How to Draw Magnetic Field with Help of Magnetic Compass and Bar Magnet

• Let's take a compass and a bar magnet
• But the compass near the north pole of the magnet
• Mark a dot where the compass needle points, mark point as point B
• Now put the other end of compass near point B
• Mark point where the compass needle points as point C
• Similarly, keep plotting until you reach the South Pole
• Now, join the points

The line formed is magnetic field line