Science Chapter 9

Question 1

What do Magnets attract?

Answer 1

Magnets attract object made of magnetic materials

Question 2

What are some examples of magnetic materials?

Answer 2

Iron, Nickel and Cobalt, alloys, stainless steel

Question 3

What object are made of stainless steels

Answer 3

Spoons,Fork and Knife

Question 4

What are Permanent magnets made of

Answer 4

Magnetically Hard materials such as steel

Question 5

What function does Permanent magnets have

Answer 5

They retain their magnetisation once magnetised

Question 6

What are an example of Magnetically soft material

Answer 6

Iron

Question 7

What are the disadvantage of Magnetically soft material

Answer 7

they lose their magnetisation easily.

Question 8

What is the advantage for magnetically soft materials

Answer 8

They are suitable for temporary magnets such as electromagnets

Question 9

What are Magnetic Poles

Answer 9

Magnetic Poles are the parts of a magnet that exert the greatest force.

Question 10

What do Magnetic poles occur in

Answer 10

pairs called North(N) and South(S)

Question 11

Why poles are called north and south

Answer 11

A magnet suspended so that it can rotate freely and horizontally will eventually settle down with one pole facing north and the other facing south

The pole is therefore called the ‘north seeking pole’

Question 12

What colour is north

Answer 12

blue

Question 13

What colour is south

Answer 13

red

Question 14

What does alike poles react

Answer 14

They repel

Question 15

What does unlike poles react

Answer 15

They attract

Question 16

What is the direction of North Poles

Answer 16

Out

Question 17

What is the direction of South Poles

Answer 17

In

Question 18

What is Magnetic Field

Answer 18

Magnetic field is a volume of space where magnetic force is exerted

Question 19

All magnets are surrounded by magnetic fields.
True or Flase

Answer 19

True

Question 20

How can the shape of a magnetic field be shown

Answer 20

iron fillings or plotting compases

Question 21

State all the uses of electromagnets

Answer 21

-Scrap yard crane

Question 22

Explain how electromagnets work

Answer 22

The iron core of the electromagnet is a soft magnetic material.

When current flows the iron becomes strongly magnetised and so picks up the scrap iron and steel.

When the current is turned off, iron loses its magnetisation and so releases the scrap.

Question 23

What are Earth’s magnetic field caused by

Answer 23

electric currents flowing through the molten outer core of the Earth

Question 24

What shape is similiar to the magnetic field

Answer 24

around a bar magnet

Question 25

What is the origin of Earth’s Magnetic Field

Answer 25

The spinning of the metalic Inner core and convection currents in the metalic outer core creates a magnetic field around the earth

Question 26

How can magnetism be induced in a magnetic material

Answer 26

If the magnetic material is placed within a magnetic field.

Question 27

What if the magnetically hard material is removed from the field

Answer 27

It will retain its magnetism

Question 28

What is Lodestone

Answer 28

a rock in Earth’s crust

Question 29

What does electromagnets consists of

Answer 29

IT consists of a current carrying coil wrapped around an iron coil

Question 30

How do electromagnets differ from normal magnets

Answer 30

They are made by passing an electric current through a wire that has been wrapped around iron. The current creates a magnetic field and magnetises the iron core.

When the current is turned off, the iron loses its magnetism.

Question 31

What do magnetic materials include?

Answer 31

Metals iron nickel and cobalt

Question 32

What are permanent magnets

Answer 32

Magnets with magnetic field that are always there, you cannot switch it on and off

Question 33

How is an electromagnet made

Answer 33

wrapping a wire around a magnetic material, such as iron. The wire that is wrapped around is called a COIL. Material in the middle of the coil is called the CORE

Question 34

How to find out which pole is it of an electromagnet

Answer 34

• Use a magnetic compass that points along magnetic line field, it will point toward the south pole
• Use a bar magnet with known poles. To attract unlike poles and repel like poles. With this you can bring bar magnet to electromagnet detect which pole is which

Question 35

Give examples of applications of electromagnet

Answer 35

-Fire door,held with an electromagnet. Fire alarm switched on, the magnet is switched off and door closes

-Toaster, the handle is pushed down, an electromagnet holds down a metal basket with bread in it. A timer turns the electromagnet off and the metal basket pops up with toast.

Question 36

3 things that are needed to make an electromagnet

Answer 36

-a coil of wire
- a magnetic core inside the coil
- an electric current flowing in the coil

Question 37

factors that will affect the strength of an electromagnet

Answer 37

-more turns in the coil, the stronger the electromagnet
- material of the core. Iron and some types of steel in the core make the strongest electromagnets
- current in coil, the greater the current the stronger the electromagnet

Question 38

What should you do when increasing the number of turns on the coil

Answer 38

Keep the current and core the same

Question 39

What should you do when using more cells to increase the current.

Answer 39

Keep the number of turns on the coil and core the same

Question 40

What should you do when using a soft iron core in place of a steel core

Answer 40

Keep the number of turns on the coil and the current the same

Question 41

Suggest two changes to the electromagnet that would make the pointed end of the nail become the south pole(originally north pole)

Answer 41

1. Reversing the direction of the current
2. Turn the pointed nail around towards the other direction.