NCERT Class 10 Science : Learning Concept
Science: Chapter 13-Magnetic Effects of Electric Current-Concepts
13.1 Magnetic Field and Field Lines
Previously we have studied the properties of permanent magnets. A magnet had always two poles, North Pole and South Pole. Like poles will repel and unlike poles will attract each other. As magnets have two poles, we have explained these properties by the existence of many small dipoles inside a magnet.
We also studied about electricity, and learned that if a potential difference is created between two points, current flows through a wire.
Then scientists found that a current carrying wire behaves like a magnet. When a magnet is moved near a wire it shows electrical properties. Our previous learning about magnetic dipoles and charges carrying current individually could not explain the effect of current on magnet and vice versa. This behavior is better explained with magnetic field and electric field.
Magnetic Field and Field Lines:
The region surrounding a magnet, in which the force of the magnet can be detected, is said to have a magnetic field.
Field lines are one of the ways to visualize the strength and direction of a magnetic field.
Figure 1: Magnetic Field and Field Lines