Topic 7 Magnetism And Electromagnetism

Question 1

What do all magnets have?

Answer 1

North (north seeking) pole
South (south seeking) pole

Question 2

What do all magnets produce?

Answer 2

Magnetic field

Question 3

What is a magnetic field?

Answer 3

Region around magnet where force acts on another magnet or magnetic material

Question 4

What are 4 magnetic materials?

Answer 4

Iron
Steel
Cobalt
Nickel

Question 5

What type of force are attraction and repulsion between magnetic poles?

Answer 5

Non contact

Question 6

What are the 2 types of magnet?

Answer 6

Permanent
Induced

Question 7

What does a permanent magnet produce its own?

Answer 7

Magnetic field

Question 8

What is an induced magnet?

Answer 8

Material become magnet when placed in magnetic field

Question 9

What is the force always between permanent and induced magnets?

Answer 9

Attraction

Question 10

What happens to an induced magnet when it’s removed from the magnetic field?

Answer 10

Quickly loses magnetism

Question 11

What is the force always between a magnet and a magnetic material?

Answer 11

Attractive

Question 12

Where on a magnet are the magnetic forces strongest?

Answer 12

Poles

Question 13

Where on a magnet is the magnetic field strongest?

Answer 13

Poles

Question 14

What happens when 2 magnets are bought close together?

Answer 14

Exert a force on each other

Question 15

Where does the direction of a magnetic field line go from?

Answer 15

North Pole to South Pole

Question 16

What is the direction of the magnetic field at any point given by?

Answer 16

Direction of force that would act on another North Pole placed at that point

Question 17

What happens the closer you get to a magnet?

Answer 17

Field is stronger

Question 18

What do closer together magnetic field lines indicate?

Answer 18

Stronger field

Question 19

What does a magnetic compass contain?

Answer 19

Tiny bar magnet

Question 20

Why does a compass point in the direction of the magnetic field it is in?

Answer 20

North Pole of its magnet attracted to South Pole of any magnet its near

Question 21

Why do compasses always point north when they’re not near a magnet?

Answer 21

Earth generates own magnetic field, shows core of earth must be magnetic

Question 22

What is produced when a current flows through a wire?

Answer 22

Magnetic field around wire

Question 23

What 2 things does the strength of the magnetic field produced around a wire depend on?

Answer 23

Current through wire
Distance from wire

Question 24

What is the shape of a magnetic field around a wire?

Answer 24

Concentric circles

Question 25

What **rule** can be used to **work out** the **direction of current** and **direction of magnetic field around a wire**?

Answer 25

**Right hand thumb rule (direction of curled fingers = direction of field)**

Question 26

What is a **solenoid**?

Answer 26

**Coil of wire**

Question 27

How can you **increase the strength of the magnetic field created by current through a wire**?

Answer 27

**Shape wire into solenoid**

Question 28

Why does **wrapping wire into a coil (a solenoid) increase the strength of its magnetic field**?

Answer 28

**Field lines around each loop of wire line up, lots of field lines pointing in same direction** and **very close together**

Question 29

What are **2 words** to **describe the magnetic field inside a solenoid**?

Answer 29

**Strong** and **uniform**

Question 30

What does the **magnetic field around a solenoid have a similar shape to**?

Answer 30

**Bar magnet**

Question 31

How can you **increase** the **field strength** of a **solenoid**?

Answer 31

Add **iron core**

Question 32

What does an **iron core in a solenoid become whenever current is flowing**?

Answer 32

**Induced magnet**

Question 33

What is an **electromagnet**?

Answer 33

**Solenoid** with an **iron core** (**magnet** whose **magnetic field** can be **turned on and off** with **current**)

Question 34

What **3 things** does the **force acting on a conductor in a magnetic field depend on**?

Answer 34

**Magnetic flux density** (how many field lines in region) **Size of current** **Length of conductor**

Question 35

For a **conductor at 90 degrees to a magnetic field** and **carrying a current**, what is the **equation** to find the **force** acting on it?

Answer 35

**Force = magnetic flux density x current x length**

Question 36

What is the **motor effect**?

Answer 36

When **conductor carrying current is placed in magnetic field**, **magnet producing the field** and **conductor exert a force on each other**

Question 37

In the **motor effect**, what does the **wire have to be at to experience the full force**?

Answer 37

**90 degrees to magnetic field**

Question 38

What **2 things** does the **force always act at right angles to** in the **motor effect**?

Answer 38

**Magnetic field of magnets** **Direction of current in wire**

Question 39

What **rule** can you use to **find the direction of the force** in the **motor effect**?

Answer 39

**Flemings left hand rule**

Question 40

What does your **First finger show in Flemings left hand rule**?

Answer 40

**Direction of field**

Question 41

What does your **seCond finger in Flemings left hand rule show**?

Answer 41

**Direction of current**

Question 42

What does your **thuMb show in Flemings left hand rule**?

Answer 42

**Direction of force**