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Electromagnetic Waves Flashcards

(64 cards)

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1
Q

Order from longest wavelength

A
  • radio waves
  • microwaves
  • infra red
  • visible light
  • ultra violet
  • x rays
  • gamma rays
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2
Q

Order from highest frequency

A
  • gamma rays
  • x rays
  • ultra violet
  • visible light
  • infrared
  • microwaves
  • radio waves
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3
Q

What type of wave are electromagnetic waves

A

Transverse waves

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4
Q

What’s the relationship between wavelength and frequency

A

They are inversely related

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5
Q

What does ionising mean

A

Damaging to our cells

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6
Q

Which waves are ionising

A
  • ultraviolet
  • X rays
  • gamma rays
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7
Q

What can happen to electromagnetic waves when interacting with other objects

A

They can be absorbed, reflected or transmitted

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8
Q

Which type of electromagnetic waves can be used in communication

A
  • radio waves
  • microwaves
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9
Q

What are electromagnetic waves made up of

A

Oscillating electric and magnetic fields

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10
Q

How do radio waves generate electricity

A

They use alternating currents
- made up of oscillating charges

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11
Q

What device do you use to generate radio waves

A

Transmitter connected to an oscilloscope

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12
Q

What is an oscilloscope used for

A

To see the frequency of an alternating current

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13
Q

What does an alternating current do

A

Determines the frequency of the wave

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14
Q

What is the name of the device in which we detect the generated radio wave

A

Receiver connected to an oscilloscope k

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15
Q

Radio waves -
The frequency generated is the same as the frequency received what does this allow us to do

A

Allows us to transfer information

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16
Q

What is the main use for radio waves

A

Communication

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17
Q

How far can long radio waves travel

A

HUGE distances

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18
Q

How far can short radiowaves travel

A

Long distances

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19
Q

How do very short radio waves travel

A

Directly from the transmitter to the receiver

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20
Q

How do long radio waves travel

A

Distract (bend) around the curved surface of the earth

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21
Q

How do short radio waves travel

A

Reflected off the ionosphere

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22
Q

What is the ionosphere

A

Electrically charged layer of the upper surface

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23
Q

What are microwaves that aren’t absorbed by water molecules used for

A

Communication

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24
Q

What is the use for microwave that are absorbed by water

A

To heat up our food

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25
How do microwaves that aren’t absorbed by water work
Using satellites Microwaves have to pass through the earths atmosphere Once they reach the satellite they’re received and then transmitted back to earth On Earth we detect them using a satellite dish
26
How do microwaves that are absorbed by water work
In microwaves - microwaves are fired at our food The heat from the waves get absorbed by the water molecules As the water molecules vibrate more they transfer energy to the neighbouring molecules So it spreads throughout the food via conduction and convection
27
What is infrared radiation
Radiation emitted from all objects that have thermal energy
28
What’s the relationship with infrared radiation and heat
The hotter an object is the more infrared radiation will be emitted
29
What are 3 uses of infrared radiation
Infrared camera Cooking Electric heaters
30
How does an infrared camera work
See in the dark to spot living organisms Organisms will appear bright as they are hotter so emit more radiation
31
How does an oven work using infrared radiation
Heat up the oven which emits infrared radiation Heat up the food by transferring the heat energy
32
Why in an oven does food crisp but in a microwave it will only continue to get hotter
Infrared radiation doesn’t penetrate the surface of the food causing it to crisp Microwaves do penetrate and absorb the water molecules
33
How do electric heaters work
Use electrical energy to heat up the metal of the heater So hot it emits infrared radiation to the surroundings Heat up rooms
34
Are microwaves and infrared radiation harmful
Only in high quantities
35
What is the colour of the longest wavelength for visible light
Red
36
What is the colour of the shortest wavelength for visible light
Violet
37
What does ROYGBIV stand for
Red Orange Yellow Green Blue Indigo Violet
38
How do we see different colours
Light we use to see appear different colours depending on the wavelength
39
What can visible light be used for
Communication Through optical fibres or Copper wires and electricity
40
How do optical fibres work
They are thin glass or plastic Can transmit pulses of light long distances The light is reflected every time it hits the surface
41
Why are optical fibres good
They can transmit data quickly Can transmit more info than copper wires Less likely to be distorted than copper wires
42
What materials need to be used for transmitting visible light
Materials that will reflect the light - not absorbing Reflection is specular - NOT diffuse
43
Instead of optical fibres what can be used
Copper wires and electricity
44
Does uv have a higher or lower frequency than visible light
Un has a higher frequency than visible light
45
Does uv have a longer or shorter wavelength than visible light
Uv has a Shorter wavelength than visible light
46
What are 4 uses for uv
Most common: sun emits uv - get a tan/burn Fluorescence Security Sterilise water
47
How does fluorescence work
UV light is absorbed Energy is re emitted as visible light
48
How do fluorescent slights work
Generate uv Absorbed by a layer of phosphorus that cotes the inside of a glass bulb So much energy it re-emits the energy as visible light
49
What’s a benefit of fluorescent lights
Energy efficient
50
What’s the use of uv in security
Security pens - write codes that are completely invisible until we shine a uv light on them Can do the same with passports and bank notes (money)
51
How is uv used to sterilise water
Destroys microorganisms
52
What are x rays used for
To view the internal structure of objects (Eg. Our bodies)
53
How does an x ray machine work
By firing x rays through a persons body Recording the rays that get through using a detecter plate The x rays are absorbed by bones They only pass partially through fleshy parts eg heart Image starts off white Goes black if that area of the detector plate receives radiation
54
What colour are bones shown as on x rays
White
55
What are x rays used for
Detect broken bones Detect other diseases
56
Are x rays harmful
A bit, they give a person a small amount of radiation (Most of the time it’s worth taking the risk)
57
Who experience the most danger when x rays are being fired
The staff involved
58
What do the staff do to prevent from the harm of x rays
Leave the room Wear a lead lined apron
59
What’s a benefit of doing an x ray
It’s a quick cheap test
60
What are gamma rays used for
Used for medical imaging Used to treat cancer (radiotherapy) Used to sterilise things eg medical equipment/ food
61
What’s a benefit of gamma rays
They can destroy microorganisms without causing any other damage
62
Positive about using gamma rays to kill microorganisms on food
Keeps food fresh for longer still face to eat
63
Positive of gamma rays and x rays in medicine
Can help us diagnose and treat diseases
64
Negatives of gamma rays and x rays in medicine
Both are ionising radiation Can damage our cells Can lead to cancer

Physics (10 decks)

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