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Physics LC2 > Electromagnetic spectrum > Flashcards

Electromagnetic spectrum Flashcards

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1
Q

What are all electromagnetic waves?

A

Transverse waves that travel at the same speed (or velocity) in a vacuum.

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2
Q

What is the order of electromagnetic waves from highest frequency to lowest?

A 
Gamma
X-ray
Ultraviolet
Visible
Infrared
Microwave
Radio
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3
Q

As you move from gamma rays to radio waves what happens to the wavelengths?

A

Wavelengths increase

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4
Q

As you move from the gamma rays to radio waves, what happens to the frequencies?

A

Frequencies decrease

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5
Q

What do electromagnetic waves transfer?

A

They transfer energy from the source of the wave to an absorber of the wave.

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6
Q

Gamma rays carry the most ____ of all the electromagnetic waves.

A

Energy

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7
Q

What are gamma rays used for?

A

Medical imaging and therapy, astronomy, sterilisation and food preservation.

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8
Q

What are the risks of gamma ray usage?

A

Gamma rays are extremely penetrating and damaging to living tissues and cells.

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9
Q

What can we use gamma rays to destroy?

A

Bacteria and tumours

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10
Q

What can X-rays penetrate?

A 
Soft materials (like body tissue).
- Bones are dense materials that absorb X-rays. We can use X-rays to build a shaded image of bones and body tissue.
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11
Q

What are X-rays used for?

A

Medical and industrial imaging, to treat cancer and for security purposes to detect weapons in airports (and other places)

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12
Q

X-rays are highly _____?

A

Ionising

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13
Q

What does highly ionising mean?

A

Can damage body cells

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14
Q

What are the safety precautions when dealing with X-rays?

A

Minimum exposure, appropriate shielding

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15
Q

Where is ultraviolet light on the spectrum?

A

Between X-rays and visible light

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16
Q

What happens atomically in UV lamps?

A

In lamps, UV photons excite (gives energy to) atoms. The atoms then release visible light.

17
Q

What are the risks of UV light?

A

Exposure to too much ultraviolet light can cause skin burns, skin cancer and cataract formations in the eye.

18
Q

What is Ultraviolet light used for?

A

medical and forensic photography, air purification, disinfection and medical therapy and to detect fake bank notes

19
Q

What are the risks of Infra-red radiation?

A

serious skin burns if emitted from high-intensity sources.

20
Q

What is infra-red radiation used for?

A

TV controls, security purposes –> intruder alarms by detecting body heat.

21
Q

How is infra-red used to cook food?

A

The frequency is high enough to excite particles in food. This increases their temperature.

22
Q

What are microwaves used for?

A

Satellite communications, transmit signal from a nearby phone mast to a mobile phone.

23
Q

Why are microwaves useful for cooking food?

A

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.

24
Q

How to microwaves travel through the atmosphere?

A

In straight lines. This makes them good for transmitting signals.

25
Q

Microwaves have a high enough frequency to…

A

penetrate the Earth’s atmosphere and to reach satellites.

26
Q

Why are microwaves dangerous to humans?

A

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

27
Q

What safety precautions can we take to reduce any exposure to microwaves?

A

Always have some sort of shielding between the source of microwaves and living tissue.
An example of this is the protective shielding on microwave ovens.

28
Q

What are radio waves used for?

A

RAdio waves are used for radio and TV communications.

29
Q

Radio waves have ____ wavelengths?

A

Long, they can therefore be sent around the Earth’s surface and around buildings without interference.

30
Q

Why are radio waves potentially harmful?

A

At high intensities, radio waves can cause internal heating of living tissue.

31
Q

How can electromagnetic waves be produced?

A

By electrical circuits and by changes in atoms.

32
Q

How do gamma rays originate?

A

From changes in the nucleus of an atom

33
Q

What is visible light used for?

A

To see the world around and in fibre optics

34
Q

Why do we use visible light in optical fibres?

A

because it can be totally internally reflected. This means that we can transmit signals along optical fibres without the signal getting lost.

35
Q

If an object reflects all wavelengths equally, what colour is the object?

A

White

Physics LC2 (8 decks)

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