Topic 3.3 - Electromagnetic Spectrum

Question 1

State the 7 electromagnetic waves found in the electromagnetic spectrum in order of increasing wavelength

Answer 1

Gamma, X Ray, UV, Visible, Infrared, Microwaves, Radio

Question 1

What is the highest frequency electromagnetic wave?

Answer 1

Gamma waves

Question 2

What is the highest energy electromagnetic wave?

Answer 2

Gamma wave

Question 3

What is the speed of EM waves in a vacuum?

Answer 3

3x10⁸ m/s

Question 4

A wave transmits energy from…

Answer 4

…source to absorber.
e.g. from a light source to the eye

Question 5

What range of frequencies of electromagnetic waves can be detected by the human eye?

Answer 5

400-700 nanometres

Question 6

What properties are shared by all electromagnetic waves?

Answer 6

• They are all transverse waves
• They all travel at the same speed (3 x 10⁸m/s) in a vacuum
• They can travel through a vacuum

Question 7

State and explain a use of radio waves.

Answer 7

Communications, because radio waves are long wavelength and can travel long distances without losing quality.

Question 8

State and explain a use of microwaves.

Answer 8

• Microwaves are used for the purpose of satellite communications (transmitting signals between stations on Earth and satellites).
• Microwaves are also used to transmit signal from a nearby phone mast (transmitter) to a mobile phone.
• Microwaves are absorbed by water, heating up the water in the process. This makes microwaves useful for cooking food because food contains lots of water.

Question 9

State uses of infrared radiation.

Answer 9

• Infra-red radiation is used in TV controls
• Infra-red can also be used for security purposes such as in intruder alarms by detecting body heat.

Question 10

State and explain uses of UV radiation.

Answer 10

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

Question 11

State and explain uses of X rays.

Answer 11

• Low-energy X-rays are used for medical and industrial imaging.
• High-energy X-rays are used to treat cancer.
• X-rays are also used for security purposes to detect weapons in airports (and other places).

Question 12

State and explain uses of gamma rays.

Answer 12

• Gamma rays are used in medical treatments, such as radiotherapy in the treatment of cancer.
• Astronomy
• Food preservation

Question 13

How does UV radiation affect body tissue?

Answer 13

• UV radiation can cause cancer when skin is exposed to it.
• It can cause blindness if eyes are overexposed to UV radiation.

Question 14

How do X-rays affect body tissue?

Answer 14

X-rays are ionising so they can damage or kill cells and cause mutations that could lead to cancer.

Question 15

How do gamma rays affect body tissue?

Answer 15

Gamma rays are even more ionising than X-rays, so they can cause cell mutations (which can lead to cancer) and cell death.

Question 16

What are the safety precautions taken while using X-Rays?

Answer 16

• Due to the dangerous nature of X-rays, exposure to X-rays should always be kept to a minimum.
• People working with X-ray equipment should always shield themselves to prevent exposure to X-rays.
• These people will place materials (metals for example lead) between themselves and the X-rays.

Question 17

What are the risks of Infra-red radiation

Answer 17

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

Question 18

What are the risks of microwaves (the actual wave)?

Answer 18

• Because humans are largely made up of water, exposure to microwaves could have a harmful effect.

Question 19

What are risks of radio waves?

Answer 19

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