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GCSE Physics P1, P2, P3 > P2 - Radiation and life > Flashcards

P2 - Radiation and life Flashcards

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1
Q

What is light a type of?

A

A type of Electromagnetic Radiation (EM radiation).

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2
Q

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

A

The Electromagnetic radiation (i.e. light)

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3
Q

Some of the things that we see are called what?

What do they emit? How do they emit this?

A

Some of the things that we see are LIGHT SOURCES.

They EMIT LIGHT, often by GLOWING HOT.

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4
Q

Everything else that we see ____ light.

A

REFLECTS

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5
Q

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

A

ABSORBS

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6
Q

Light is one part of the ____________.

A

ELECTROMAGNETIC SPECTRUM

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7
Q

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

A

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

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8
Q

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

A

Increasing frequency

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9
Q

Waves with higher frequencies carry…?

A

MORE energy

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10
Q

What are photons?

A

Packets of energy that electromagnetic waves transfer.

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11
Q

The energy in a photon depends only on the….

A

Frequency of the wave.

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12
Q

Increasing the frequency of an electromagnetic wave…

A

increases the energy of its photons.

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13
Q

What is the order of the electromagnetic spectrum?

A

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

Increases Frequency, Decreases Wavelength

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14
Q

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

A

INTENSITY

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15
Q

What two things do intensity depend on?

A
  1. The number of photons per second (intensity increases with number of photons)
  2. The energy transferred by each photon (intensity increases with energy).
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16
Q

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

A

…moves away from its source.

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17
Q

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

A

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

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18
Q

The intensity of an EM wave is the…

A

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

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19
Q

What are the units of intensity?

A

J / m^2 / s

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20
Q

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

A

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

21
Q

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

A

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

22
Q

What happens in ionisation?

A

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.

23
Q

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

A
  1. high energy ULTRAVIOLET
  2. X-rays
  3. Gamma Rays
24
Q

Radioactive materials emit…

A

GAMMA rays.

25
Q

Gamma rays pass…

A

easily through the human body.

26
Q

X-rays pass through…

A

muscle but are ABSORBED by the bone.

27
Q

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

A

They become ionised and damaged.

28
Q

What can the damaged cells either do?

A

DIE or DEVELOP INTO CANCER.

29
Q

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

A

Because X-rays are absorbed by dense materials.

30
Q

How do radiographers in hospitals protect from the ionising radiation?

A

By LEAD and CONCRETE screens.

31
Q

Things which absorb radiation….

A

HEAT UP.

32
Q

Cells which absorb radiation are….

A

damaged if they get too hot.

33
Q

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

A

Increasing its exposure time and intensity.

34
Q

Why are microwaves good to heat objects containing water?

A

Microwaves are strongly absorbed by water molecules.

35
Q

How do microwaves protect people from the radiation?

A

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

36
Q

Mobile phone networks use _______________.

A

LOW INTENSITY microwaves.

37
Q

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

A

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

38
Q

Sunlight contains….

A

ULTRAVIOLET radiation.

39
Q

Ultraviolet radiation can cause:

A

Sunburn and skin cancer.

40
Q

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

A

Sunscreens and clothings.

They absorb UV radiation emitted by the Sun.

41
Q

What is Ozone (O3) ?

A

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.

42
Q

Increased exposure to UV radiation can increase the risk of?

A

developing SKIN cancer

43
Q

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

A

4%

44
Q

UV radiation from the Sun causes what?

A

Chemical changes to molecules in the ozone layer.

45
Q

How does the Earth warm up?

A

When it absorbs radiation from the Sun.

46
Q

What does the Earth do to cool itself down?

A

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

47
Q

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

A

GREENHOUSE EFFECT.

48
Q

Everything emits some EM radiation with a…

A

RANGE of frequencies

49
Q

The PRINCIPAL FREQUENCY of that radiation is…

A

the one with greatest intensity.

GCSE Physics P1, P2, P3 (3 decks)

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