P2 - Radiation and Life

Question 1

Define the intensity of electromagnetic radiation.

Answer 1

The amount of energy arriving at a square metre of surface per second.

Question 2

Why does the intensity of radiation decrease with distance?

Answer 2

• Photons spread out as they travel.
• Some photons get absorbed by particles.
• Some photons are reflected and scattered by other particles.

Question 3

How do microwaves protect us from radiation?

Answer 3

They have a metal case and wire screen in the door.

Question 4

Draw and label The Carbon Cycle.

Answer 4

Question 5

How can deforestation affect The Carbon Cycle?

Answer 5

• It adds more CO₂ to the atmosphere.
• It prevents as much photosynthesis happening, so less CO₂ is removed.

Question 6

How can burning fossil fuels affect The Carbon Cycle?

Answer 6

• It releases carbon dioxide that has been “locked up” ever since.

Question 7

What knock-on effects can Global warming have?

Answer 7

• Climate change - Crops may not be able to grow in some areas.
• Extreme weather - e.g: Hurricanes.
• Rising sea levels - Melting ice caps and higher sea temperatures may cause sea levels to rise, flooding low-lying land.

Question 8

How do AM (Amplitude modulation) and FM (Frequency modulation) differ?

Answer 8

• AM changes the carrier wave based on the signal wave.
• FM changes the signal wave based on the carrier wave.

Question 9

Why are Microwaves used for satellite TV?

Answer 9

• They are reflected well by metals, so satellite dishes are made from metal.

Question 10

What are the 7 types of radiation in the Electromagnetic Spectrum in order?

Answer 10

• Radio waves.
• Microwaves.
• Infrared waves.
• Visible light.
• Ultraviolet rays.
• X-Rays.
• Gamma rays.

Question 11

What is “intensity”?

Answer 11

The number of photons delivered per second and the amount of energy each packet contains, i.e: the photon energy.

Question 12

If a cell is irradiated, what might happen to it?

Answer 12

• Nothing.
• Mutate - can lead to cancer.
• Die - can lead to burns, sickness and even death.

Question 13

Why are ions dangerous?

Answer 13

Because they are highly reactive and can take part in other chemical reactions.

Question 14

Name some greenhouse gases.

Answer 14

• Carbon dioxide.
• Water vapour.
• Methane.
• Nitrous oxide.

Question 15

Why are radio waves used for transmitting radio and TV programmes?

Answer 15

Because they aren’t strongly absorbed by the atmosphere.

Question 16

Why are visible light and infrared waves used for carrying information?

Answer 16

Because they can travel huge distances down fibre-optic wires without becoming significantly weaker and can be boosted at intervals.

Question 17

Why are X-Rays used?

Answer 17

Because they are absorbed by dense materials, so can be used to produce shadow pictures of bones and ‘see’ inside of luggage at airport security checks.

Question 18

What are the benefits of using digital signals?

Answer 18

• Interference can be easily removed because it only has two states.
• No loss in quality over distance.
• No effect in quality during amplification.