Magnetism

Question 1

Define Magnetic Induction

Answer 1

Process whereby a magnetic object becomes a magnet when near/in contact with a magnet

Question 2

List the 3 Magnetisation Methods

Answer 2

1. Placing near a Permamagnet
2. Stroking
3. Electrical Method

Question 3

Explain how the Electrical Method works in magnetisation

Answer 3

Direct current passes through the solenoid and produces a strong B-field, causing the magnetic object inside the solenoid to be magentised

Question 4

List the 3 ways to increase the strength of a magnet through the Electrical Method of magnetisation

Answer 4

1. Increasing Current (I)
2. Increasing no. if turns per unit length of solenoid
3. Using a soft iron core that concentrates magnetic field lines

Question 5

State the difference between the properties of Temporary Magnets and Permanent Magents

Answer 5

Temporary Magnet: Soft Magnetic Material
-Easily magnetised and demagnetised
-Loses magnetism easily when removed from B-field

Permanent Magnet: Hard Magnetic Material
-Difficult to magnetise and demagnetise
-Retains magnetism for a long time

Question 6

Define B-Field

Answer 6

Region in which a magnetic object, placed within the influence of a magnetic field, experiences a magnetic force

Question 7

List the 4 steps in plotting a B-field

Answer 7

1. Place bar magnet in the centre of paper with North pole facing North
2. Place plotting compass near one pole of the magnet. Mark North and South Ends of the compass needle
3. Reposition compass such that the South Needle is pointing to the North marking of the previous postion
4. Repeat steps 2 and 3 until several traces are drawn. Directions of B-field lines are indicated by the direction of the needle

Question 8

State the 4 properties of B-fields

Answer 8

1. The direction of field lines start from the North pole and end at the South pole
2. The field lines do not intersect
3. Density of field lines indicate the strength of the field
4. Field patterns are symmetrical