Electromagnetic

Question 1

Define a permanent magnet

Answer 1

They produced thier own magnetic field

Question 2

What are permanent magnets made of

Answer 2

Steel and impurities like aluminium

Question 3

What is the magnetic field

Answer 3

A region where are the magnet magnetic materials experience a noncontact force

Question 4

What are induced magnet

Answer 4

Magnetic material that turn into a magnet when put into a magnetic field
Permanent magnets always attract induced magnets

Question 5

What happens when current flows through a wire

Answer 5

A magnetic field is created around the wire

Question 6

What does changing the direction of current do

Answer 6

It changes the direction of the magnetic field

Question 7

Describe the right hand thumb rule

Answer 7

Point Your thumb in the direction of current and call your fingers around this is the direction of the field

Question 8

How can you increase the strength of the magnetic field of a wire

Answer 8

Play rappin’ the wire into a coil called a solenoids

Question 9

Why do solenoids have a stronger magnetic field than a normal wire

Answer 9

Because the field lines line up with each other
Therefore ther are lots of field lines pointing in the same direction and that are very close together

Question 10

What do the ends of a solenoid act like

Answer 10

The north and south pole of a bar magnet

Question 11

How can u increase the field streangth of a solenoid

Answer 11

By putting an iron core which becomes an induced magnet
However if you stop the current the magnetic field disappears as it is an electromagnetic

Question 12

What is the difference between a magnet and an electromagnet

Answer 12

You can turn electro on and off

Question 13

What is the motor effect

Answer 13

When a current carrying wire is placed between magnetic poles , the magnetic fields of the poles and the wire interact which causes them to exert a force on each other .

Question 14

How can the wire experience full force in the motor effect

Answer 14

The wire has to be at 90 degrees to the magnetic field as if it is parallel it will not experience any force
This is because force always acts at right angles to the magnetic field

Question 15

What happens when current flows through the conductor

Answer 15

Force increases

Question 16

What is the magnetic flux density

Answer 16

How many field lines are in a strength region which shows thev of the region

Question 17

What does the force acting on a conductor in a magnetic field depend on

Answer 17

The magnetic flux density
The size of the current through conductor
And the length of the conductor in the magnetic feild

Question 18

What equation is used when the current is at 90 degrees to the magnetic field

Answer 18

F= BIL
Force = magnet flux density x current x length

Question 19

What is exerted on any current carrying conductor

Answer 19

Force

Question 20

How can u find the direction of force on a current carrying conductor

Answer 20

Flemings left hand rule

Question 21

Explain Flemings left hand rule

Answer 21

Using ur left hand point your first finger in the direction of the magnetic field
Second finger in the direction of current
Your thumb will show direction of force

Question 22

How can you increase the force on a copper rod in experiment with a magnet and a circuit

Answer 22

Decrease the resistance of a variable resistor in the circuit
Use a stronger magnet

Question 23

What is the name of the effect used by a moving coil loudspeaker to produce sound waves

Answer 23

Motor effect

Question 24

Explain how a moving coil loudspeaker produces a sound wave

Answer 24

The current through the coil creates a magnetic field which interacts with the permanent magnetic field of a magnet
Therefore it produces a resultant force causing the coil to move producing sound waves
When direction of current reverses the direction of force will also reverse

Question 25

A power supply has an alternator connected to a transformer transformer can be adjusted to have different numbers of terms on the coiled explain why

Answer 25

To vary the potential difference so you do not need a generator for each type of power supply device

Question 26

In a simple DC motor how is an alternating current introduced in the coil

Answer 26

The coil move through the magnetic field of the polls on either side
So potential difference is induced across the coil
Therefore there is a complete circuit so current is also induced in the coil
Every half term the potential difference reverses direction so the current country reverse direction

Question 27

Why are there slip rings on a DC motor

Answer 27

Stop wire from twisting together

Question 28

The alternator from a portable power supply is disconnected from the transformer explain why the handle of the alternator becomes easier to turn

Answer 28

Because there’s no induced current so no magnetic field produced to oppose the movement of the coil

Question 29

What is the function of a microphone

Answer 29

To convert soundwaves into variations in current

Question 30

Quarter of a soil annoyed is to iron rods explain why they move apart when current is flowing through them

Answer 30

The roads become induced magnets with the same polarity therefore they repell

Question 31

Why does the movement of a bar magnet induce a pd across a coil

Answer 31

As the magnetic failed around the coil changes