Chapter 13: Magnetic Effects of Electric Current

Magnet

• Attracts iron, cobalt & nickel.
• Freely suspended magnet aligns in North-South direction.

Uses of Magnets

• Radio & stereo speakers
• Refrigerator doors
• Audio & video cassette players
• Computer hard disks & floppies
• Children’s toys

Magnetic Field & Field Lines

The region around a magnet where magnetic force is experienced.

• Field lines represent magnetic field direction and magnitude.
• They don’t intersect, are closed curves, and flow from North to South pole outside the magnet.

Right Hand Thumb Rule

If current flows in the direction of the thumb, the fingers show the direction of magnetic field lines.

Magnetic Field of a Loop and Solenoid

• Field strength is inversely proportional to radius, directly proportional to number of turns and current.

Solenoid

• Cylinder-shaped coil of many turns of insulated copper wire.
• Magnetic field similar to bar magnet.

Electromagnet

Made using solenoid wound around a soft iron core.

Fleming’s Left Hand Rule

Thumb – Force, Forefinger – Magnetic Field, Middle Finger – Current

Electric Motor

• Converts electric energy to mechanical energy.
• Based on force on a current-carrying conductor in magnetic field.

Electromagnetic Induction

Production of current due to change in magnetic field.

Fleming’s Right Hand Rule

Thumb – Motion, Forefinger – Field, Middle Finger – Induced Current

Electric Generator

Converts mechanical energy to electric energy. Types: AC & DC

Domestic Electric Circuits

• AC Supply: 220V, 50Hz
• Live (Red), Neutral (Black), Earth (Green)

Important Diagrams

Formative Assessment I

HOTS Questions

Oral Questions