Radiation (EM Spectrum)

Question 1

Give one use of ultraviolet.

Answer 1

• security marking
• detecting forged bank notes
• fluorescent lamps

Question 2

Which wave in the electromagnetic spectrum has the longest wavelength?

Answer 2

Radio waves have the longest wavelength.

Question 3

In what way is UV (ultraviolet) a danger?

Answer 3

Too much exposure to UV can cause skin cancer.

Question 4

Give one application of microwaves.

Answer 4

• heating food
• mobile phone communications

Question 5

How does UV (ultraviolet) benefit human health?

Answer 5

UV helps generate vitamin D for healthy skin.

Question 6

What do all waves in the electromagnetic spectrum have in common?

Answer 6

All waves in the electromagnetic spectrum travel at the same speed (the speed of light).

Question 7

Give one use of infrared.

Answer 7

• thermal imaging
• remote controls
• security systems (motion sensor)

Question 8

Which wave in the electromagnetic spectrum has the least energy?

Answer 8

Radio waves have the least energy.

Question 9

Give one use of X-rays.

Answer 9

• medical X-ray scans
• airport security scanners

Question 10

State a detector of infrared radiation.

Answer 10

• photodiode
• phototransistor
• thermistor
• thermocouple

Question 11

Give one application of radio waves.

Answer 11

• Broadcasting
• Satellite transmissions
• Communications

Question 12

What speed do all waves in the electromagnetic spectrum travel at?

Answer 12

All waves in the electromagnetic spectrum travel at the speed of light - 3 x 10⁸ ms^-1.

Question 13

Which wave in the electromagnetic spectrum has the shortest wavelength?

Answer 13

Gamma rays have the shortest wavelength.

Question 14

How is the frequency of a wave in the e.m. spectrum related to its energy?

Answer 14

The higher the frequency of a wave in the e.m. spectrum, the more energy the wave has.

Question 15

State a detector of UV (ultraviolet).

Answer 15

Fluorescent material can be used to detect UV.
This can be in the form of special ink, or chemicals in washing powder.

Question 16

Give one application of gamma rays.

Answer 16

• sterilising food and medical equipment
• treating cancer
• medical tracers

Question 17

State a detector of radio waves.

Answer 17

An aerial is used to detect radio waves.

Question 18

Name the seven different types of waves in the electromagnetic spectrum.

Try to list them from long λ (wavelength) to short λ.

Answer 18

Radio (long λ)

Microwaves

Infrared

Visible

Ultraviolet

X-rays

Gamma rays (short λ)

Question 19

Give one use of visible light.

Answer 19

• photography
• illumination
  
  • car headlights
  • street lighting
  • barcode scanner at checkout

Question 20

What type of radiation does a laser emit?

Answer 20

A laser will emit one single frequency (and wavelength) of ‘light’. Normally this is visible light (e.g. red, green, blue) but it possible to get infrared lasers.

Question 21

Which wave in the electromagnetic spectrum has the greatest energy?

Answer 21

Gamma rays have the greatest energy.

Question 22

Complete the following sentence:

All waves carry ……………

Answer 22

All waves carry energy.

Question 23

Describe what is meant by gamma radiation.

Answer 23

• Gamma radiation is a wave in the electromagnetic spectrum
• Gamma rays have no mass or charge
• Gamma rays have a very short wavelength and a high frequency

Question 24

Explain how an X-ray image is produced.

Answer 24

X-rays are directed towards an object (e.g. suspected broken bone, metal weld).
X-rays are absorbed by dense material such as bone. This shows up as white on photographic film.
X-rays will pass through gaps or low-density material. This will show up as black on photographic film.

Question 25

Explain how UV (ultraviolet) is used to check security markings (e.g. on banknotes).

Answer 25

The UV causes special chemicals (fluorescent material) to glow / give off visible light.

Question 26

Which material(s) can X-rays pass through?
1. Metal
2. Bone
3. Skin

Answer 26

X-rays can pass through C. skin.

(Bone is too dense for X-rays to fully pass through, and metal will reflect the X-rays)

(thanks to Nathan for this question)