Magnets and magnetic fields

Question 1

Magnetic field

Answer 1

any region of space where magnetic forces can be felt

Question 2

Demonstration of a magnetic field due to a current in a long straight wire

Answer 2

Each end of wire is connected to d.c supply with high current

To demonstrate magnetic field use iron fillings

Question 3

Plot a magnetic field due to a bar magnet

Answer 3

Put a bar magnet on sheet of paper
Put a plotting compass next to one pole of the magnet mark with dots on the paper both ends of the compass needle
Move the compass
mark the other end of the needle
Repeat and join dots with smooth curved line

Question 4

Determining the direction of a magnetic field due to an electric current

Answer 4

Right hand grip

Question 5

Solenoid

Answer 5

A coil of wire whose length is much longer than its radius

Question 6

Electromagnet

Answer 6

Consists of a soft iron core
When current is switched on the core acts as a magnet and used to pick up nails

Question 7

Use of electro magnets

Answer 7

Electric motors
Loudspeakers

Question 8

The earth’s magnetic field

Answer 8

Used for accurate navigation
Protect the earth from dangerous radiation from the sun