Magnetism And Electromagnetism Paper 2

Question 1

What is Fleming’s left hand rule?

Answer 1

Thumb is force (motion)
Index finger is magnetic field
Middle finger is current

Question 2

What happens when u put a moving wire with a complete circuit within a magnetic field?

Answer 2

It will induce a current that is alternating relative to the direction of the wire moving.

Question 3

What happens when a moving wire with an incomplete circuit is put into a magnetic field?

Answer 3

It will induce potential difference that is alternating relative to the wire’s direction of movement.

Question 4

What are 3 ways a generator can be altered to increase the potential difference?

Answer 4

Increase number of coils in wire
Increase speed of wire’s movement
Increase strength of magnetic field

Question 5

What happens when current flows through a wire?

Answer 5

It produces a magnetic field

Question 6

What is a solenoid?

Answer 6

A wire shaped into a coil

Question 7

Name magnetic metals

Answer 7

Iron, cobalt, nickle

Question 8

What is an induced magnet?

Answer 8

A material that becomes magnetic when placed into a magnetic field

Question 9

What is the motor effect?

Answer 9

When a wire that is carrying a current produces a magnetic field with in turn causes a resultant force to exert force onto the wire

Question 10

How are alternators used to produce an A.C current?

Answer 10

A coil of wire is placed into a magnetic field. This is connected to 2 slip rings, which allows current to pass through to an external circuit. Potential difference alternates due to the wire rotating, which in turn causes the current to alternate.

Question 11

How does potential difference alternate in the wire?

Answer 11

When horizontal (parallel to the magnet), the potential difference is at its highest. However, when vertical (perpendicular to the magnet) the potential difference is at zero.

Question 12

How do dynamos produce D.C current?

Answer 12

A rotating is placed into a magnetic field. A split ring is used to allow current to constantly flow in one direction.

Question 13

How is the magnetic field’s strength around a wire affected?

Answer 13

Distance from wire
Magnitude of current

Question 14

What can affect the strength of a solenoid?

Answer 14

NO. of coils
current in wire

Question 15

Soleniod + iron core =?

Answer 15

Electromagnet

Question 16

How can a solenoid be used in a door lock?

Answer 16

When the switch is pressed, current flows through the coil
The iron core becomes magnetised and attracts the iron bolt
The door can then be opened

Question 17

How are electrical signals converted into sound waves in a speaker?

Answer 17

An alternating current is sent through the coil, which generates an electromagnetic field
The electromagnetic field and the permanent magnet interact, generating a force
The force makes the cone move
The alternating current constantly changes the direction of the force
This makes the cone vibrate forwards and backwards
The cone’s vibrations create variations in air pressure (sound waves)
As a result, sound is produced

Question 18

What is the generator effect?

Answer 18

Moving a wire (conductor) at right angles to a magnetic field which induces p.d to produce a current

Question 19

How do sound waves convert into electrical signals in a microphone?

Answer 19

sound waves hit the diaphragm of a microphone
The diaphragm is a thin membrane that vibrates with the same frequency and amplitude as the sound wave
The diaphragm passes the vibrations on to the coil
The coil moves within the magnetic field, which generates a current.

Question 20

How do transformers work?

Answer 20

An alternating current flows into the primary coil
The primary coil is a solenoid and it induces a magnetic field
The iron core magnetises and demagnetises as the current changes
The changing magnetic field passes through the secondary coil and induces a potential difference in it
If the secondary coil is part of a complete circuit, an alternating current flows through the circuit

Question 21

What are step up transformers?

Answer 21

Have more turns in secondary coil than primary and this increases potential difference

Question 22

What are step down transformers?

Answer 22

They have more turns in primary coil than secondary and this decreases potential difference