CP5

Question 1

What are electromagnetic waves?

Answer 1

A group of waves that all travel at the same speed in a vacuum, and are all transverse.

Question 2

What happens to electromagnetic waves once they pass an interface (boundary)?

Answer 2

They get faster or slower and change direction depending on the type of medium they go into.

Question 3

What are frequencies that our eyes can detect called?

Answer 3

Visible light.

Question 4

What colours appears with lower and higher frequencies?

Answer 4

Lower frequencies=Redish colour
Higher frequencies=Blueish colour

Question 5

Why can a prism be used to split visible light into the colours of the spectrum?

Answer 5

As different frequencies slow down at different amounts, so they are bent by different angles.

Question 6

What type of waves are all electromagnetic waves?

Answer 6

They are all transverse waves.

Question 7

What speed do all electromagnetic waves travel in a vacuum?

Answer 7

3x10ˆ8 m/s.

Question 8

Who was the first person to investigate infrared radiation?

Answer 8

It was William Herschel.

Question 9

What did William Herschel notice when investigating infrared radiation?

Answer 9

He noticed that different colours contained different amounts of heat.

Question 10

How can you investigate refraction?

Answer 10

By measuring the angles between light rays and the normal to see how different angles and strength of waves affect refraction between media.

Question 11

What is the incident ray in a refraction practical?

Answer 11

The light ray approaching the interface.

Question 12

What is the angle of incidence in a refraction practical?

Answer 12

The angle between the incident ray and the normal.

Question 13

What is the angle of refraction in a refraction practical?

Answer 13

The angle between the normal and the light leaving the normal.

Question 14

What is the visible spectrum?

Answer 14

The part of the electromagnetic spectrum that can be detected by the human eye.

Question 15

What is the electromagnetic spectrum?

Answer 15

The entire frequency range of electromagnetic waves.

Question 16

What are the seven colours in the visible spectrum?

Answer 16

1. Red
2. Orange
3. Yellow
4. Green
5. Blue
6. Indigo
7. Violet

Question 17

What is the full range of the electromagnetic spectrum (from shortest wavelengths to longest)?

Answer 17

1. Gamma rays
2. X-rays
3. Ultraviolet
4. Visible light
5. Infrared radiation
6. Microwaves
7. Radiowaves

Question 18

How is visible light used in our lives?

Answer 18

1. Light bulbs are designed to emit visible light
2. Cameras detect visible light and record images

Question 19

How is Infrared used in our life?

Answer 19

1. Can be used for communication at short ranges (e.g. between a tv remote and a tv)
2. A grill which transfers energy to food by infrared radiation to heat it up
3. Security cameras which sometimes have sensors that detect infrared radiation emitted by intruders

Question 20

How are Microwaves used in our life?

Answer 20

1. For communication (e.g. satellite transmissions and mobile phone signals)
2. Heating up food in microwaves by transferring energy to the food

Question 21

How are Radiowaves used in our life?

Answer 21

For transmitting radio broadcasts and TV programmes.

Question 22

How are Radiowaves produced?

Answer 22

They are produced by oscillations in electrical currents. A metal rod/wire can be used as an aerial to receive radio waves. The radio waves are absorbed by the metal and cause oscillations in electric circuits connected to the aerial.

Question 23

What are Oscillations?

Answer 23

Variations in current and voltage.

Question 24

Do waves change direction when travelling?

Answer 24

No, waves travel in a straight line unless they are reflected/refracted.

Question 25

How can some radio waves be refracted in the atmosphere?

Answer 25

Some frequencies of radio waves can be refracted by a layer in the atmosphere called the ionosphere. If radio waves reach the ionosphere at a suitable angle, they may be refracted enough to send them back to Earth.

Question 26

Are Microwaves refracted in the atmosphere or not?

Answer 26

No, Microwaves are not refracted in the Earth's atmosphere.

Question 27

How is Ultraviolet used in our life?

Answer 27

It can be used to disinfect water by killing microorganisms in it.

Question 27

What is a fluorescent material?

Answer 27

A material that absorbs ultraviolet radiation and re-emits it as visible light.

Question 28

When are fluorescent materials used in our lives?

Answer 28

1. In security markings that are only visible when ultraviolet light shines on them 2. In low energy light bulbs as they have a gas inside of them that produces ultraviolet radiation when an electric current passes through it and a coating on the inside of the glass absorbs the ultraviolet and emits visible light

Question 29

Why are X-rays useful?

Answer 29

As they can pass through many materials that visible light cannot such as muscles and fat.

Question 30

How are X-rays used in our lives?

Answer 30

1. To make images of the inside of the body (the bones) 2. To examine the insides of metal objects 3. To inspect luggage in airport security scanners

Question 31

What can Gamma rays do that X-rays can't?

Answer 31

1. Transfer a lot of energy 2. Kill cells 3. Pass through all the materials in the body

Question 32

How are Gamma rays used in our lives?

Answer 32

1. To sterilize food and surgical equipment by killing potentially harmful organisms 2. To kill cancer cells in Radiotherapy 3. To detect cancer

Question 33

How can Gamma rays be used to detect cancer?

Answer 33

1. A chemical that emits gamma rays is injected into the blood. This chemical is designed to collect inside cancer cells. 2. A scanner outside the body then locates the cancer by finding the source of the gamma rays. This is possible as gamma rays can pass through all the materials in the body.

Question 34

What is radiotherapy?

Answer 34

The use of ionizing radiation to treat diseases, such as to kill cancer cells.

Question 35

Why might microwaves be dangerous to humans?

Answer 35

As our bodies are mostly water and so the microwaves could heat cells from the inside.

Question 36

Why might infrared radiation be dangerous to humans?

Answer 36

Our skin absorbs infrared radiation, which we feel as heat. Too much infrared radiation can damage or destroy cells, causing burns to the skin.

Question 37

Which types of waves (high frequency or low frequency) are more dangerous and why?

Answer 37

Higher-frequency waves transfer more energy than low-frequency waves and so are potentially more dangerous.

Question 38

Why might ultraviolet radiation be dangerous to humans?

Answer 38

The energy transferred by ultraviolet radiation to our cells can cause sunburn and damage DNA. Too much exposure to ultraviolet radiation can lead to skin cancer. It can also damage our eyes.

Question 39

How can you protect your skin from ultraviolet radiation?

Answer 39

1. By staying out of the strongest sunshine 2. By Covering up with clothes and hats 3. By using sun cream with a high SPF (sun protection factor) 4. Using sunglasses

Question 40

Why might X-rays/Gamma rays be dangerous to humans?

Answer 40

They can penetrate the body. Excessive exposure to X-rays/Gamma rays may cause mutations in DNA that can kill cells or cause cancer.

Question 41

How is electromagnetic radiation produced?

Answer 41

By changes in the electrons or the nuclei in atoms. Changes in the nuclei/atoms produce a form of electromagnetic radiation.