P2 - Radiation and life

Question 1

What is light a type of?

Answer 1

A type of Electromagnetic Radiation (EM radiation).

Question 2

You only see things only when your eyes (detectors) absorb what?

Answer 2

The Electromagnetic radiation (i.e. light)

Question 3

Some of the things that we see are called what?

What do they emit? How do they emit this?

Answer 3

Some of the things that we see are LIGHT SOURCES.

They EMIT LIGHT, often by GLOWING HOT.

Question 4

Everything else that we see ____ light.

Answer 4

REFLECTS

Question 5

Black objects don’t reflect much light, they mostly _____ it.

Answer 5

ABSORBS

Question 6

Light is one part of the ____________.

Answer 6

ELECTROMAGNETIC SPECTRUM

Question 7

All waves in the electromagnetic spectrum ______ through a _____ at 300 000 km/s.

Answer 7

All waves in the electromagnetic spectrum TRANSMIT through a VACUUM at 300 000 km/s.

Question 8

The energy of a waves in the spectrum increases with…..?

Answer 8

Increasing frequency

Question 9

Waves with higher frequencies carry…?

Answer 9

MORE energy

Question 10

What are photons?

Answer 10

Packets of energy that electromagnetic waves transfer.

Question 11

The energy in a photon depends only on the….

Answer 11

Frequency of the wave.

Question 12

Increasing the frequency of an electromagnetic wave…

Answer 12

increases the energy of its photons.

Question 13

What is the order of the electromagnetic spectrum?

Answer 13

RADIO WAVES, MICROWAVES, INFRARED, VISIBLE LIGHT, ULTRAVIOLET, X-RAYS, GAMMA RAYS

Increases Frequency, Decreases Wavelength

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Question 14

The energy absorbed in each second from an electromagnetic wave depends on its _____

Answer 14

INTENSITY

Question 15

What two things do intensity depend on?

Answer 15

1. The number of photons per second (intensity increases with number of photons)
2. The energy transferred by each photon (intensity increases with energy).

Question 16

The energy of a wave is spread over an increasing area as it…

Answer 16

…moves away from its source.

Question 17

The intensity of the wave decreases with ____ distance from its source

Answer 17

The intensity of the wave decreases with increasing distance from its source

Question 18

The intensity of an EM wave is the…

Answer 18

…energy transferred to each SQUARE METRE of absorbing surface in EACH SECOND.

Question 19

What are the units of intensity?

Answer 19

J / m^2 / s

Question 20

The intensity of a wave in a vacuum is ___________ to the ____ of its distance from its source.

Answer 20

The intensity of a wave in a vacuum is INVERSELY PROPORTIONAL to the SQUARE of its distance from its source.

Question 21

If the wave is partially absorbed by the medium it is passing through, the….

Answer 21

…intensity drops even more rapidly than an inverse square law.

Question 22

What happens in ionisation?

Answer 22

When a photon hits an atom or a molecule, it sometimes has enough energy to REMOVE AN ELECTRON and change the atom or molecule, which can initiate other chemical reactions.

Question 23

What are the only three ionising radiations in the EM spectrum?

Answer 23

1. high energy ULTRAVIOLET
2. X-rays
3. Gamma Rays

Question 24

Radioactive materials emit…

Answer 24

GAMMA rays.

Question 25

Gamma rays pass...

Answer 25

easily through the human body.

Question 26

X-rays pass through...

Answer 26

muscle but are ABSORBED by the bone.

Question 27

When cells absorb gamma rays or X-rays what happens to them?

Answer 27

They become ionised and damaged.

Question 28

What can the damaged cells either do?

Answer 28

DIE or DEVELOP INTO CANCER.

Question 29

Why are X-rays used to make shadow pictures of people's bones or their luggage?

Answer 29

Because X-rays are absorbed by dense materials.

Question 30

How do radiographers in hospitals protect from the ionising radiation?

Answer 30

By LEAD and CONCRETE screens.

Question 31

Things which absorb radiation....

Answer 31

HEAT UP.

Question 32

Cells which absorb radiation are....

Answer 32

damaged if they get too hot.

Question 33

You can increase the thermal energy transferred from radiation by doing what?

Answer 33

Increasing its exposure time and intensity.

Question 34

Why are microwaves good to heat objects containing water?

Answer 34

Microwaves are strongly absorbed by water molecules.

Question 35

How do microwaves protect people from the radiation?

Answer 35

Microwaves inside the machine reflect off the metal in the walls and door or are absorbed by them instead of escaping.

Question 36

Mobile phone networks use _______________.

Answer 36

LOW INTENSITY microwaves.

Question 37

How is the risk of cell damage from mobile phones measured?

Answer 37

By comparing cancer rates in large groups of people who do and do not use mobile phones.

Question 38

Sunlight contains....

Answer 38

ULTRAVIOLET radiation.

Question 39

Ultraviolet radiation can cause:

Answer 39

Sunburn and skin cancer.

Question 40

What 2 things can protect people? How do they protect them?

Answer 40

Sunscreens and clothings. | They absorb UV radiation emitted by the Sun.

Question 41

What is Ozone (O3) ?

Answer 41

A layer at the top of the atmosphere that absorbs UV radiation from the Sun. This protects living things on Earth from some of the harmful effects of UV radiation.

Question 42

Increased exposure to UV radiation can increase the risk of?

Answer 42

developing SKIN cancer

Question 43

If the ozone layer thins by 1%, the risk of skin cancer increases by about...

Answer 43

4%

Question 44

UV radiation from the Sun causes what?

Answer 44

Chemical changes to molecules in the ozone layer.

Question 45

How does the Earth warm up?

Answer 45

When it absorbs radiation from the Sun.

Question 46

What does the Earth do to cool itself down?

Answer 46

Emits Infrared radiation which can either pass into space, reflect off clouds, or radiate back from gases which absorb it.

Question 47

When the Earth's radiation is absorbed or reflected back, this keeps the Earth warmer. This is called the...

Answer 47

GREENHOUSE EFFECT.

Question 48

Everything emits some EM radiation with a...

Answer 48

RANGE of frequencies

Question 49

The PRINCIPAL FREQUENCY of that radiation is...

Answer 49

the one with greatest intensity.