Give one reason why an electromagnet would be used rather than a permanent magnet.

Answer 1

An atom has a small, positively-charged nucleus surrounded by orbiting negatively-charged electrons. The electrons are arranged at different distances from the nucleus (different energy levels).

Answer 2

Atoms are very small and have a radius of about 1 × 10-10 metres.

The radius of a nucleus is less than \frac{1}{10,000}
10,000
1
​
of the radius of an atom but most of the mass is concentrated in the nucleus.

Question 3

Electrons are arranged at different distances from the nucleus. What are these distances known as?

Answer 3

Energy levels

Question 4

There are three different sub-atomic particles; each has a different charge

Answer 4

Protons are positively charged.
Neutrons have no charge.
Electrons are negatively charged.
The overall charge of an atom is neutral (no charge).

Answer 5

Protons are found in the nucleus. They have a relative charge of +1.

An element’s atomic number is the number of protons it possesses. This means that all atoms of the same element have the same number of protons.

Answer 6

Electrons are found in fixed orbits around the nucleus. They have a relative charge of −1.

Question 7

Which of the following particles has a relative charge of +1?

Answer 7

Proton

Answer 8

Neutrons are found in the nucleus. They have a relative charge of 0.

Atoms also have no overall electric charge as the number of electrons equals the number of protons.

Question 9

What is the overall charge of an atom?

Answer 9

0

Question 10

Fill in the charges of the different sub-atomic particles:

Answer 10

1
Proton = +1
2
Neutron = 0
3
Electron = −1

Question 11

Magnetism

ebi: find key words from the question in the senecca area instead

Answer 12

Magnetism describes the ability of magnets to attract and repel other magnets without touching them.

Answer 13

Magnets have a north pole (N) and south pole (S). If two magnets are close enough to each other, then the south pole of one magnet will attract the north pole of the other magnet.

Question 14

What is the term given to the ability of magnets to attract and repel other magnets without touching them?

Answer 14

Magnetism

Answer 15

If one magnet is turned so that both south poles (or both north poles) are close together, then the magnets will repel each other.

Opposite poles on a magnet attract.
Like poles on a magnet repel.
These are both examples of non-contact forces.

Question 16

What are the names given to the two poles on a magnet?

Answer 16

North pole

South pole

Answer 17

The forces between magnets (magnetic forces) are caused by invisible magnetic fields.

A magnetic field is the area around a magnet where another magnet or magnetic material (iron, nickel, cobalt and steel) feels a force.

Question 18

What type of force causes magnets to attract and repel one anoth

Answer 18

Non-contact forces

Answer 19

The strength of a magnetic field depends on the distance from the magnet. The magnetic field is strongest at the magnet’s poles.

Question 20

Where is a magnetic field strongest?

Answer 20

At the poles

Question 21

Electromangentic Waves

Answer 22

Electromagnetic waves are transverse waves that travel at the same speed in a vacuum. To simplify things, we assume that the speed of EM waves in air is the same as that in a vacuum.

Answer 23

There is a continuous spectrum of EM waves. EM waves transfer energy from the source of the wave to an absorber of the wave and this depends on two factors:

Frequency.
Wavelength.

Question 24

What type of wave are electromagnetic waves?

Answer 24

Transverse

Answer 25

Wave energy increases with frequency and decreases with wavelength.

Therefore waves with the lowest frequency have the greatest wavelength and waves with the greatest frequency have the shortest wavelength.

Question 26

Give the two factors that influence the EM spectrum:

Answer 26

Wavelength

Frequency

Question 27

The EM spectrum can be split into seven types of wave (in order of highest frequency to lowest frequency):

Answer 27

Gamma.
X-ray.
Ultraviolet (UV).
Visible.
Infrared.
Microwave.
Radio waves.

Question 28

If Gamma rays have the highest frequency in the EM spectrum, what is their wavelength relative to the rest of the spectrum?

Answer 28

the shortest wavelength

Question 29

Give two types of wave in the electromagnetic spectrum:

Answer 29

Gamma

X-ray

Question 30

Electromagnetic spectrum

Answer 31

Gamma rays carry the most energy of all electromagnetic waves.

They are used in medical imaging and therapy, astronomy, sterilisation and food preservation.

Answer 32

A risk of gamma rays are that they are extremely penetrating and damaging to living tissues and cells.

Question 33

Two uses of gamma rays:

Answer 33

Steralisation

astronomy

Answer 34

X-rays carry the second most energy of all the waves in the electromagnetic spectrum.

Low-energy X-rays are used for medical and industrial imaging and high-energy X-rays are used to treat cancer. They are also used for security purposes to detect weapons in airports.

Question 35

Why are gamma rays dangerous?

Answer 35

They penetrate and dammage living cells

Answer 36

X-rays are dangerous because they are highly ionising which can damage body cells, even in low doses. Exposure to X-rays should always be kept to a minimum and people should use materials (e.g. metals or lead) to protect themselves.

Question 37

Which of these are uses of X-rays?

Answer 37

treating cancer

medical imaging

Answer 38

Ultraviolet light is found between X-rays and visible light in the electromagnetic spectrum.

It is used in medical and forensic photography, air purification, disinfection and medical therapy. UV light can also be used to detect fake bank notes.

Answer 39

Exposure to too much ultraviolet light can cause skin burns, skin cancer and cataract formations in the eye.

Question 40

What two types of EM waves is Ultraviolet light found between in the EM spectr

Answer 40

X-rays

visible light

Answer 41

Visible light is in the middle of the EM spectrum. We use visible light to see the world around us.

Traditionally, we say that there are seven colours of light in the spectrum - red, orange, yellow, green, blue, indigo and violet.

Answer 42

Infra-red radiation is the next wave in the electromagnetic spectrum.

It is used in TV controls and for security purposes, such as in intruder alarms by detecting body heat.

Answer 43

Infra-red radiation can cause serious skin burns if emitted from high-intensity sources.

Answer 44

Microwaves are the 6th type of wave in the electromagnetic spectrum.

Microwaves are used in satellite communications, transmitting signals between mobile phones and for heating up water to cook food.

Answer 45

Because humans are largely made up of water, exposure to microwaves could have a harmful effect. Safety precautions can be used to help reduce the impact of microwaves. Protective shielding is installed on microwave ovens to prevent exposure.

Answer 46

Radio waves are the lowest frequency waves in the EM spectrum. They are used for radio and TV communications.

Answer 47

At high intensities, radio waves can cause internal heating of living tissue with potentially harmful effects.

Question 48

Give three types of wave in the electromagnetic spectrum:

Answer 48

Radio
Microwave
Gamma