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Science > EMR > Flashcards

EMR Flashcards

1
Q

What is the wavelength?

A

The distance between two successive waves

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2
Q

What is the amplitude?

A

The maximum distance a wave extends beyond its middle position

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3
Q

What is the wave equation?

A

If the frequency of a wave increases, the wavelength decreases and vice versa

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4
Q

How is electromagnetic radiation produced?

A

When electrical charges move a magnetic field is generated and vice versa

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5
Q

What are the different types of EMR radiation?

A

Radio waves, microwaves, infrared, visible light, ultraviolet, x rays and gamma rays

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6
Q

What speed do all EMR waves travel at?

A

300,000 km/s

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7
Q

What are the different colours in the visible light spectrum?

A

Red, orange, yellow, green, blue, indigo, violet

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8
Q

What is white and black light?

A

White light is all the colours in the visible spectrum, black light is the absence of colour

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9
Q

Why do we see objects in colour?

A

Because all objects absorb some colours and reflect some e.g a red apples reflects red and absorbs every other colour

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10
Q

What are the three primary colours?

A

Red, green and blue

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11
Q

What are the three secondary colours?

A

Cyan, magenta and yellow

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12
Q

How does colour blindness work?

A

We have three cones in our eyes for the three different primary colours and if one doesn’t work then we don’t see that colour

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13
Q

What happens when we mix different pigments?

A

We are subtracting wavelengths so we are doing colour subtraction

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14
Q

What happens when we mix light?

A

We are adding extra wavelengths so it is colour addition

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15
Q

What types of communication use radio waves?

A

Television and radio networks

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16
Q

How do short-wave radio signals work?

A

The waves beam upwards at an angle and are reflected off the ionosphere back onto earth

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17
Q

Why are long radio waves good for communication?

A

Because they can bend around the Earths surface

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18
Q

How do AM and FM waves travel?

A

By using a carrier wave

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19
Q

How do carrier waves work?

A

They travel along with the radio wave and after being detected by the antenna of a radio they are subtracted, leaving just the audio signal

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20
Q

What happens in AM waves when the carrier is subtracted?

A

The frequency stays the same as the carrier but the amplitude varies

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21
Q

What happens in FM waves when the carrier is subtracted?

A

The amplitude is the same as the carrier but the frequency varies

22
Q

Which have a shorter wavelength: FM or AM?

A

FM

23
Q

Why are AM waves used more often?

A

Because they can travel around large obstacles more easily than FM waves and can also travel further

24
Q

What is frequency?

A

The number of waves produced each second

25
Q

What are microwaves used for?

A

In radar and communications systems and also sometimes cooking

26
Q

Why are microwaves used in cooking?

A

Because they are absorbed by the food, causing the molecules to heat up

27
Q

What materials don’t absorb or reflect microwaves?

A

Glass, paper and plastics don’t absorb and metals reflect.

28
Q

How is it heat transferred from the sun to the Earth?

A

By infrared radiation

29
Q

What are the two types of signals?

A

Analogue and Digital

30
Q

What signal do we use most often?

A

Digital

31
Q

What type of number systems do digital signals use?

A

The binary number system (0’s and 1’s or ons and offs)

32
Q

How does optic fibre work?

A

Digital light pulses from a laser, travels along glass fibres being reflected inside the fibre

33
Q

How do ADSL modems work?

A

They send digital signals down copper wires designed for analogue signals. A splitter is used to split the analogue from the digital

34
Q

What type of EMR wave do mobile phones use?

A

Microwaves

35
Q

How do mobile phones work?

A

Each phone sends the message by line of sight to a base station. The message is moved between base stations using copper cable or optic fibre

36
Q

How does television work?

A

It is transmitted by UHF and VHF radio waves. They use digital signal because it is more reliable

37
Q

What is the wavelength of a radio wave?

A

1m-2km

38
Q

What are radio waves used for?

A

Radio and TV channels and communication

39
Q

What is the wavelength of microwaves?

A

1mm-1m

40
Q

What are microwaves used for?

A

Cooking and communication such as mobile phones and the Internet

41
Q

What is the wavelength of infrared radiation?

A

750nm-1mm

42
Q

What is infrared used for?

A

Getting heat from the sun to the earth and night-vision

43
Q

What is the wavelength of Visible Light?

A

750nm-480nm

44
Q

What is visible light used for?

A

Enables us to see things (duh), DVD players and lightbulbs

45
Q

What is the wavelength of ultra violet waves?

A

480nm-100nm

46
Q

What is ultra violet used for?

A

Sun tanning, killing microbes, sterilising food and detecting forged bank notes

47
Q

What is the wavelength of X-Rays?

A

100nm-10nm

48
Q

What are X-Rays used for?

A

See inside people and airport security

49
Q

What is the wavelength of Gamma Rays?

A

10nm-10pm

50
Q

What are gamma Rays used for?

A

Kill cancer cells-radiotherapy, sterilise food and medical equipment

Science (12 decks)

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