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Physics > 3 The electromagnetic spectrum > Flashcards

3 The electromagnetic spectrum Flashcards

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1
Q

What is the electromagnetic spectrum?

A

A spectrum that includes a family of waves like radio waves, microwaves, infrared, visible light, ultraviolet and x-rays.

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2
Q

How is the electromagnetic spectrum ordered?

A

On the left of the spectrum, the waves have a very long wavelength and low frequency. On the right of the spectrum, the waves have a very short wavelength and high frequency.

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3
Q

What kind of properties do the waves on the electromagnetic spectrum have?

A
  • They all transfer energy.
  • They are all transverse waves.
  • They all travel at 3x10^8 m/s which is the speed of light in a vacuum.
  • They can all be reflected and refracted.
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4
Q

What is the order of the names of the electromagnetic spectrum?

A
  • Radio waves
  • Microwaves
  • Infrared radiation
  • Visible light
  • Ultraviolet
  • X-rays
  • Gamma rays
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5
Q

What is the order of colours of the electromagnetic spectrum?

A
  • Red
  • Orange
  • Yellow
  • Green
  • Blue
  • Indigo
  • Violet
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6
Q

Which kind of waves carry the most energy?

A

Gamma rays.

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7
Q

Why do gamma rays carry the most energy?

A

They have the shortest wavelengths and highest frequencies.

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8
Q

What is a short description of radio waves and what do they do?

A
  • They have the longest wavelengths on the electromagnetic spectrum and are mainly used for communication.
  • They are used for broadcasting and communications.
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9
Q

How do radio waves work?

A

They are given out (emitted) by a transmitter. As they arrive at an aerial they are detected and the information they carry can be received.

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10
Q

What are the uses of microwaves?

A

They are used for communications, radar and cooking foods, radar uses radio waves to find the positions of things.

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11
Q

How do microwaves work to cook food?

A

The food placed in a microwave cooks more quickly than in an oven because water molecules in the food absorb the microwaves and become very hot, this means that food cooks throughout and not just from the outside.

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12
Q

What problems can we have if we are exposed to microwaves?

A

They can internally heat human body tissue.

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13
Q

How do we prevent the exposure to microwaves?

A

Microwaves have metal screens that reflect microwaves and keep them inside the oven and ensure that they don’t escape.

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14
Q

How are microwaves used in communications?

A

The waves pass easily through the Earth’s atmosphere and so are used to carry signals to orbiting satellites. From here, the signals are passed on to their destination or to other orbiting satelites.

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15
Q

What is infrared used for?

A

Heaters and night vision equipment.

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16
Q

What happens to the amount emitted of infrared by an object when its heat increases?

A

It increases.

17
Q

Why are infrared waves so convenient?

A

This is because the waves are not harmful as they have a low penetrating power so they only operate over small distances; making them unlikely to interfere with other signals or waves.

18
Q

What happens if you come into contact with infrared for too long?

A

It can cause skin burns.

19
Q

What is visible light?

A

It is the part of the electromagnetic spectrum that is visible to the human eye.

20
Q

What is visible light used for?

A
  • It can be used to read compact discs and barcodes.
  • It can be sent along optical fibres, so it can be used for communication in hard-to-reach places such as inside the body of a patient.
  • Visible light can be detected by the sensors in digital cameras, and used to take still photographs or videos.
  • Information stored on DVD’s is also read using visible light.
21
Q

What are some uses of ultraviolet light?

A
  • Fluorescent lamps.
  • In security marker pens (the special ink is invisible in normal light but becomes visible in ultraviolet light).
22
Q

How do fluorescent lamps work?

A

This is because the UV light produced strikes a special coating on the surface which then emits visible light.

23
Q

What are some dangers of ultraviolet light?

A
  • It is harmful to human eyes and can damage the skin.
  • Overexposure to it while tanning can cause sunburn and blistering.
  • Skin cancer and blindness.
  • Damage to surface cells.
24
Q

How do we protect ourselves from the dangers of ultraviolet light?

A

Use protective goggles or glasses can block the UV skin rays and will reduce the harmful effects of this radiation.

25
Q

What does the ozone layer do in relation to ultraviolet light?

A

It absorbs large quantities of the suns UV radiation, and if it becomes damaged - this might lead to an increase in the amount of people who get skin cancer.

26
Q

What are x-rays used for?

A

Observing the internal structure of objects and materials, including for medical applications.

27
Q

Why can x-rays be used to check for these things?

A

This is because they pass easily through soft body tissue but can’t pass through bones, or hard structures.

28
Q

What is a danger of being exposed to x-rays?

A

They can cause cancer.

29
Q

How do you prevent the dangers of being exposed to x-rays?

A

Wear protective equipment or be behind a lead screen.

30
Q

Why do lead screens block radiation?

A

They do this due to the density of their atoms.

31
Q

What are some uses of gamma rays?

A
  • Sterilising food and medical equipment.
  • Cure cancer
32
Q

How do gamma rays sterilise things?

A

They kill microorganisms on the surface of the object.

33
Q

How do gamma rays help cure cancer?

A

Large doses of gamma rays targeted directly at the cancerous growth can be used to kill the cancer cells completely.

34
Q

What does over-exposure to gamma rays cause?

A
  • Cancer and mutation
35
Q

How do you prevent over-exposure to gamma rays?

A
  • Lead screens.
  • Boxes
  • Aprons

Physics (24 decks)

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