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Physics > CP5 > Flashcards

CP5 Flashcards

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1
Q

What are electromagnetic waves?

A

A group of waves that all travel at the same speed in a vacuum, and are all transverse.

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2
Q

What happens to electromagnetic waves once they pass an interface (boundary)?

A

They get faster or slower and change direction depending on the type of medium they go into.

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3
Q

What are frequencies that our eyes can detect called?

A

Visible light.

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4
Q

What colours appears with lower and higher frequencies?

A

Lower frequencies=Redish colour
Higher frequencies=Blueish colour

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5
Q

Why can a prism be used to split visible light into the colours of the spectrum?

A

As different frequencies slow down at different amounts, so they are bent by different angles.

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6
Q

What type of waves are all electromagnetic waves?

A

They are all transverse waves.

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7
Q

What speed do all electromagnetic waves travel in a vacuum?

A

3x10ˆ8 m/s.

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8
Q

Who was the first person to investigate infrared radiation?

A

It was William Herschel.

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9
Q

What did William Herschel notice when investigating infrared radiation?

A

He noticed that different colours contained different amounts of heat.

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10
Q

How can you investigate refraction?

A

By measuring the angles between light rays and the normal to see how different angles and strength of waves affect refraction between media.

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11
Q

What is the incident ray in a refraction practical?

A

The light ray approaching the interface.

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12
Q

What is the angle of incidence in a refraction practical?

A

The angle between the incident ray and the normal.

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13
Q

What is the angle of refraction in a refraction practical?

A

The angle between the normal and the light leaving the normal.

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14
Q

What is the visible spectrum?

A

The part of the electromagnetic spectrum that can be detected by the human eye.

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15
Q

What is the electromagnetic spectrum?

A

The entire frequency range of electromagnetic waves.

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16
Q

What are the seven colours in the visible spectrum?

A
  1. Red
  2. Orange
  3. Yellow
  4. Green
  5. Blue
  6. Indigo
  7. Violet
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17
Q

What is the full range of the electromagnetic spectrum (from shortest wavelengths to longest)?

A
  1. Gamma rays
  2. X-rays
  3. Ultraviolet
  4. Visible light
  5. Infrared radiation
  6. Microwaves
  7. Radiowaves
18
Q

How is visible light used in our lives?

A
  1. Light bulbs are designed to emit visible light
  2. Cameras detect visible light and record images
19
Q

How is Infrared used in our life?

A
  1. Can be used for communication at short ranges (e.g. between a tv remote and a tv)
  2. A grill which transfers energy to food by infrared radiation to heat it up
  3. Security cameras which sometimes have sensors that detect infrared radiation emitted by intruders
20
Q

How are Microwaves used in our life?

A
  1. For communication (e.g. satellite transmissions and mobile phone signals)
  2. Heating up food in microwaves by transferring energy to the food
21
Q

How are Radiowaves used in our life?

A

For transmitting radio broadcasts and TV programmes.

22
Q

How are Radiowaves produced?

A

They are produced by oscillations in electrical currents. A metal rod/wire can be used as an aerial to receive radio waves. The radio waves are absorbed by the metal and cause oscillations in electric circuits connected to the aerial.

23
Q

What are Oscillations?

A

Variations in current and voltage.

24
Q

Do waves change direction when travelling?

A

No, waves travel in a straight line unless they are reflected/refracted.

25
Q

How can some radio waves be refracted in the atmosphere?

A

Some frequencies of radio waves can be refracted by a layer in the atmosphere called the ionosphere. If radio waves reach the ionosphere at a suitable angle, they may be refracted enough to send them back to Earth.

26
Q

Are Microwaves refracted in the atmosphere or not?

A

No, Microwaves are not refracted in the Earth’s atmosphere.

27
Q

How is Ultraviolet used in our life?

A

It can be used to disinfect water by killing microorganisms in it.

27
Q

What is a fluorescent material?

A

A material that absorbs ultraviolet radiation and re-emits it as visible light.

28
Q

When are fluorescent materials used in our lives?

A
  1. In security markings that are only visible when ultraviolet light shines on them
  2. In low energy light bulbs as they have a gas inside of them that produces ultraviolet radiation when an electric current passes through it and a coating on the inside of the glass absorbs the ultraviolet and emits visible light
29
Q

Why are X-rays useful?

A

As they can pass through many materials that visible light cannot such as muscles and fat.

30
Q

How are X-rays used in our lives?

A
  1. To make images of the inside of the body (the bones)
  2. To examine the insides of metal objects
  3. To inspect luggage in airport security scanners
31
Q

What can Gamma rays do that X-rays can’t?

A
  1. Transfer a lot of energy
  2. Kill cells
  3. Pass through all the materials in the body
32
Q

How are Gamma rays used in our lives?

A
  1. To sterilize food and surgical equipment by killing potentially harmful organisms
  2. To kill cancer cells in Radiotherapy
  3. To detect cancer
33
Q

How can Gamma rays be used to detect cancer?

A
  1. A chemical that emits gamma rays is injected into the blood. This chemical is designed to collect inside cancer cells.
  2. A scanner outside the body then locates the cancer by finding the source of the gamma rays. This is possible as gamma rays can pass through all the materials in the body.
34
Q

What is radiotherapy?

A

The use of ionizing radiation to treat diseases, such as to kill cancer cells.

35
Q

Why might microwaves be dangerous to humans?

A

As our bodies are mostly water and so the microwaves could heat cells from the inside.

36
Q

Why might infrared radiation be dangerous to humans?

A

Our skin absorbs infrared radiation, which we feel as heat. Too much infrared radiation can damage or destroy cells, causing burns to the skin.

37
Q

Which types of waves (high frequency or low frequency) are more dangerous and why?

A

Higher-frequency waves transfer more energy than low-frequency waves and so are potentially more dangerous.

38
Q

Why might ultraviolet radiation be dangerous to humans?

A

The energy transferred by ultraviolet radiation to our cells can cause sunburn and damage DNA. Too much exposure to ultraviolet radiation can lead to skin cancer. It can also damage our eyes.

39
Q

How can you protect your skin from ultraviolet radiation?

A
  1. By staying out of the strongest sunshine
  2. By Covering up with clothes and hats
  3. By using sun cream with a high SPF (sun protection factor)
  4. Using sunglasses
40
Q

Why might X-rays/Gamma rays be dangerous to humans?

A

They can penetrate the body. Excessive exposure to X-rays/Gamma rays may cause mutations in DNA that can kill cells or cause cancer.

41
Q

How is electromagnetic radiation produced?

A

By changes in the electrons or the nuclei in atoms. Changes in the nuclei/atoms produce a form of electromagnetic radiation.

Physics (13 decks)

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