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Physics > Waves and EM Spectrum > Flashcards

Waves and EM Spectrum Flashcards

1
Q

What are waves?

A

Waves (vibrations) are a way of transferring energy with no matter being transferred

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2
Q

What are wavefronts?

A

Points on a surface where all vibrations are in phase and the same distance from the source

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3
Q

What are transverse waves?

A

Vibrations occur at right angles to the direction in which the wave is travelling

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4
Q

Examples of transverse waves:

A

Water waves

Light waves

Earthquake waves

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5
Q

What are longitudinal waves?

A

Vibrations occur at parallel to the direction in which the wave is travelling.

Includes areas of compression and rarefaction

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6
Q

Examples of longitudinal waves:

A

Sound waves

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7
Q

What is wavelength?

A

The distance from two consecutive peaks/troughs of a wave is called the wavelength

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8
Q

What is amplitude?

A

Amplitude is the maximum distance moved by a vibrating object from its equilibrium position

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9
Q

What is time period?

A

Time taken to make one complete oscillation

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10
Q

What is frequency?

A

The number of waves or vibrations passing a point per second

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11
Q

The relation between frequency and time period

A

F = 1/T

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12
Q

Wave Equation:

*Note the relation between frequency and wavelength (while wave speed is constant)

A

wave speed = frequency x wavelength

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13
Q

Law of Reflection?

A

The angle of incidence is equal to the angle of reflection

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14
Q

Properties of EM waves:

A
  • Transfer energy
  • Transverse waves
  • Travel at the speed of light in a vacuum
  • They can all be reflected and refracted
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15
Q

Order of waves:

A

Graham’s Xylophone Uses Very Interesting Musical Rhythms

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16
Q

Wavelength and frequency of waves in the EM spectrum:

A

G ➡ R

Increase in wavelength
Decrease in frequency

17
Q

Uses of gamma rays:

A
  • Sterilising medical equipment
  • Irradiation
  • Treat cancer (radiotherapy)
18
Q

Uses of X-rays:

A
  • Medical images (radiographs) of bones
  • In airports to scan luggage
  • In industry to check for cracks and faults in machinery and buildings
19
Q

Uses of UV rays:

A
  • Causes tan (tanning beds)
  • Some chemicals glow when under UV light - security marker pens
  • Detecting counterfeit notes
  • Fluorescent tubes: mercury vapor emits UV which strikes the fluorescent powder coating the inside of the tube, which then emits visible light
20
Q

Harmful effects of UV rays

A
  • Sunburn and blistering
  • Skin cancer
  • Blindness
21
Q

Protection against UV rays:

A
  • Protective goggles/ glasses

- Skin creams

22
Q

Uses of visible light:

A
  • Seeing
  • Used to read barcodes and compact disks
  • Used to read information stored on DVDs
  • Telecommunications: optical fibres
  • Photography
23
Q

Uses of IR waves:

A
  • Remote controls
  • Cooking
  • Electric fires, heaters
  • Night vision
24
Q

Properties specific to IR:

A
  • not very harmful (skin burns)

- Low penetrating power ➡ small distances ➡ interference with other signals waves is unlikely

25
Q

Uses of thermal imaging cameras:

A
  • Searching for people trapped in collapsed buildings, mines
  • Searching for criminals
  • Checking for heat loss from buildings
26
Q

Uses of microwaves:

A
  • Cooking
  • Satellite communication
  • Mobile phones (lower intensity than those for cooking)
  • Radar
27
Q

How are microwaves used for cooking?

A

Food has water molecules which absorb these microwaves and cook the food throughout

  • Reflected off of a metal casing so that they remain inside the oven
  • Rotating reflector that distributes these microwaves in all directions
28
Q

Harmful effects of microwaves:

Benefits of microwaves:

A
  • Cook living cells

- Penetrative, so can pass through walls, glass

29
Q

How are microwaves used for communication:

A

Carry signals to orbiting satelities and then are passed onto their destinations

Messages are sent using microwaves too

30
Q

Uses of radio waves:

A

Communication/Broadcasting (TV and FM radios)

Physics (8 decks)

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