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Physics - IGCSE > Ch - 15 (Electromagnetic Spectrum) > Flashcards

Ch - 15 (Electromagnetic Spectrum) Flashcards

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1
Q

What are the electromagnetic spectrum waves?

A
  • Radio waves
  • Microwaves
  • Infrared
  • Visible
  • Ultraviolet
  • X rays
  • Gamma rays

From longest wavelength (lowest frequency) to smalles wavelength and highest frequency.

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2
Q

What’s re the effects of radiation with High energy?

A
  • Highly ionising
  • Harmful toc ells and tissue causing cancer.
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3
Q

What is the effect of radiation with lower energy?

A
  • Useful for communications
  • less harmful to humans
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4
Q

Define electromagnetic waves.

A

Transverse waves that transfer energy from the source of the waves to an absorber

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5
Q

What are common properties of all waves?

A
  • They are all transverse
  • they can travel through vacuum
  • They all travel at same speed (3.0 x 10^8 m/s)
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6
Q

What is radio used for?

A

Communication (radio or tv)

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7
Q

what is the use of microwave?

A
  • Heating food
  • communication (WiFi, mobile phones, satellites)
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8
Q

What is the use of infrared waves?

A
  • remote controls
    -fibre optic communications
  • heating or cooking things
  • electrical heaters
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9
Q

What is the use of visible light?

A
  • seeing and taking photo
  • fibre optic communication
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10
Q

What is the use of ultraviolet rays?

A
  • Security marking
  • Fluorescents bulbs
  • Getting a suntan
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11
Q

What is the use of x-rays?

A
  • X - Ray images (medicine)
  • Security checking
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12
Q

What is the use of gamma rays?

A

Sterilizing medical instruments
Treating cancer

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13
Q

What is the main use of radio waves?

A

Wireless communication and heating (very High intensities)

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14
Q

What is the main use of infrared radiation?

A
  • security cameras (Used to illuminate an area without being seen, which is seen by detecting cameras)
  • Fiber optical cables
  • remote controls
  • emitted by warm objects
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15
Q

What is the range of visible light wavelength that human can detect?

A

from 750 nanometers (red light) up to 380 nanometers (Violet light)

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16
Q

What is ultraviolet responsible for?

A
  • giving a sun tan
  • When exposed, they absorb and re-emit it as visible light (also called fluorescence)
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17
Q

What is fluorescence used for?

A

Used to make secretly mark things using special ink.
Light bulbs also use it

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18
Q

What is the main use of X - rays?

A
  • Able go pass through most body tissues but are absorbed by denser parts of body (bone)
  • bones absorb the x - rays, leaving a shadow which can be seen when using a special x - Ray detector or photographic film.
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19
Q

What is the main use of gamma rays?

A
  • Kill living cells and tissues
  • effective at destroying cancerous cells
  • sterilize food and medical equipment
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20
Q

what EM waves are ionising?

A
  • Ultraviolet
  • x rays
  • gamma rays
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20
Q

what happens as the frequency of EM waves increases?

A

Energy increases

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20
Q

how does the danger associated with EM waves increase?

A
  • With frequency
  • Shorter the wavelength, the more ionizing the radiation
  • intensity of wave also plays a role
21
Q

What is the danger of radio waves?

A

Nothing

22
Q

What is the danger of microwave?

A

Possible heat damage to internal organs

23
Q

What is the danger of infrared?

A

Skin burns

24
Q

What damage is caused by visible light?

A

Bright light can cause eye damage

25
Q

What is the danger of ultraviolet?

A
  • Eye damage
  • Sunburn
  • Skin cancer
26
Q

What is the danger of X - rays?

A
  • Kills cells
  • Mutation
  • Cancer
27
Q

What is the danger of Gamma rays?

A
  • Kills cells
  • Mutations
  • cancer
28
Q

Why does microwaves cause internal heating?

A

Absorbed by water molecules

29
Q

What does ultraviolet result in?

A

Premature ageing, ionizing

30
Q

What do X - rays and gamma rays do?

A
  • penetrate through body and cause internal damage.
  • cause mutation of genes and cause cancer
31
Q

What’s re geostationary satellites used for?

A

Communicating information

32
Q

What is the use of geostationary satellites or low orbit satellites?

A
  • above earth’s equator
  • orbit the satellites in 24 hrs
  • at a height of 36, 000 km higher than polar
  • used for radio and telecommunication
33
Q

what is the characteristic of polar or low orbits satellites?

A
  • orbit around North and south poles
  • 200km above sea level
34
Q

What are the sues of polar satellites or low orbits?

A
  • monitoring weather
  • much shorter time delay
  • signals and images are much clearer
  • limited use in any one orbit
35
Q

What systems rely on long wave electromagnetic radiation?

A
  • mobile phones, wireless internet & satellite television (using microwave)
  • Bluetooth, terrestrial television signals & local radio stations (using radio waves)
  • optical fibers (using visble or infrared waves)
36
Q

What distance do radio waves transmit?

A
  • Short distances
  • Terrestrial (local) television signals, radio stations transmissions
37
Q

What wavelength are radio station signals transmitted at?

A
  • longer wavelength than terrestrial television signals
38
Q

In hilly areas does it receive terrestrial television signals or radio signals?

A

Radio signals because they are more prone to diffraction around the hills

39
Q

Does Bluetooth use waves or wires?

A

Radio waves, over short distances.

40
Q

What wavelength do Bluetooth signals have?

A
  • shorter wavelength
  • enables High rates of data transmission, but can only be used for over short distances.
  • they can pass through walls but signals get weakens
41
Q

What signals can microwave transmit?

A
  • large distances
  • used to send signals to and from satellites

-

42
Q

What properties must the microwave have when transmitted from a dish?

A
  • wavelength must be small compared to dish diameter to reduce diffraction
  • dish must be made of metal because metal reflects microwaves well.
43
Q

Why do mobile phones and wireless internet use microwaves?

A

They are not refracted, reflected or absorbed by the atmosphere or ionosphere.

44
Q

Which EM wave (s) do optical fibers use?

A
  • visible light or infrared
45
Q

Why do optical fibres use visible light and infrared?

A
  • Glass is transparent to viable and infra
  • visible light have short wavelength, infrared can carry High rates of data due to high frequency.
46
Q

What are the 2 types of signals?

A

Analogue
Digital

47
Q

Define analogues signals.

A

Vary continuously - they can take any value

48
Q

Define digital signals

A
  • can only take one of two (discrete) states
  • 1s and 0s
  • High and lows
  • On.s and off’s
49
Q

How are signals before and after?

A

Before transmission: Analogue to digital
After transmission: Digital to analogue

50
Q

What does analogue signal consist of?

A

Varying frequencies or amplitude.

Ex - analogue technology include telephone transmission and some broadcasting.

51
Q

What are the advantages of digital signal?

A
  • signal can be regenerated so there is minimal noise
  • accurate signal, range of data signals is larger (they cover longer distances)
  • increased rate of transmission of data
  • extra data can be added to check for errors.

Physics - IGCSE (24 decks)

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