Section 6 - Magnetism and Electromagnestism

Question 1

Magnets

Answer 1

• Produce two poles(north and south)

- Produce magnetic fields

Question 2

Definition of a magnetic field

Answer 2

A region where magnetic materials experience a force

Question 3

Placing the north and south poles of two permanent bar magnets near each other…

Answer 3

creates a uniform magnetic field between the two magnets

Question 4

Inducing magnetism

Answer 4

• Both poles attract magnetic materials
• When a magnet is brought near a magnetic material then that material acts as a magnet
• The magnetism has been induced by the original magnet
• The closer the magnet and the magnetic material get, the stronger the induced magnetism will be

Question 5

Factors that speed up a simple D.C. electric motor

Answer 5

• More current
• More turns on the coil
• A stronger magnetic field
• A soft iron core in the coil

Question 6

Fleming’s left hand rule

Answer 6

Thumb - motion
First finger - field
Second finger - current

Question 7

Electromagnetic induction

Answer 7

The creation of a voltage in a wire which is experiencing a change in magnetic field

Question 8

The dynamo effect

Answer 8

Using electromagnetic induction to transform kinetic energy into electrical energy

Question 9

Causing electromagnetic induction

Answer 9

An electrical conductor moves through a magnetic field OR an the magnetic field through an electrical conductor changes

Question 10

Increasing the voltage generated through electromagnetic induction

Answer 10

• Increase the strength of the magnet
• Increase the speed of the movement
• Increase the number of turns on the coil

Question 11

Current carrying wires

Answer 11

• An electric current in a material produces a magnetic field around it
• The larger the electric current, the stronger the magnetic field
• The direction of the magnetic field depends on the direction of the current

Question 12

Magnetic field around a straight wire

Answer 12

The field is made up of concentric circles with the wire in the centre

Question 13

Magnetic field around a flat circular coil

Answer 13

• The magnetic field in the centre is similar to that of a bar magnet
• There are concentric ellipses of magnetic field lines around the coil

Question 14

Magnetic field around a solenoid

Answer 14

• The magnetic field inside the current carrying solenoid is strong and uniform
• The field outside the coil is like a bar magnet
• This means that the ends of a solenoid act like the north and south poles of a bar magnet

Question 15

Magnetic materials - Soft and Hard

Answer 15

Soft - loses its induced magnetism quickly(e.g iron)

hard - keeps the induced magnetism permanently(e.g steel)

Question 16

Increasing the strength of a magnetic field around a solenoid

Answer 16

Add a magnetically soft iron core

Question 17

Dot/cross wires

Answer 17

Dot is coming out of the page

Cross is going into the page

Question 18

Solenoid

Answer 18

A cylindrical coil of wire which acts as a magnet when carrying electric current

Question 19

Charged particles moving through a magnetic field…

Answer 19

will experience a force, as long as they are not moving parallel to the field lines

Question 20

Transformers

Answer 20

• Change the size of the voltage of an alternating current
• Have two coils(primary and secondary), joined together with an iron core
• When an alternating voltage is applied across the primary coil, an alternating voltage is induced in the secondary coil

Question 21

The transformer equation

Answer 21

Input Voltage / Output Voltage = Number of turns on Primary / Number of turns on secondary

Question 22

If the transformer is described as being 100% efficient…

Answer 22

V1 * P1 = V2 * P2