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N5 Physics > Waves > Flashcards

Waves Flashcards

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1
Q

What do waves carry?

A

All waves carry energy.

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2
Q

What is the speed of sound in air?

A

340ms^-1

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3
Q

What is the speed of light in air?

A

(3.0x10^80)ms^-1

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4
Q

What is the unit for sound?

A

Decibels (dB)

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5
Q

What is frequency measured in?

A

Hertz (Hz)

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6
Q

What is the typical frequency a young person can hear?

A

A young person can typically hear between 20Hz to 20,000Hz.

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7
Q

What are frequencies above 20,000Hz called?

A

Ultrasound

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8
Q

What is “ultrasound”?

A

Ultrasound is any frequency above 20,000Hz

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9
Q

What is “frequency”?

A

Frequency is a measure of the number of waves per second passing a point.

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10
Q

What is the formula for frequency?

A

f = N / t

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11
Q

What is a “longitudinal wave”?

A

A longitudinal wave is one which the particles move backwards and forwards along the direction of travel.

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12
Q

What is wavelength measured in?

A

Metres (m)

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13
Q

What is “amplitude”?

A

Amplitude is the maximum distance a particle moves from it’s undisturbed point.

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14
Q

What is the wave equation?

A

v = f x [lambda]

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15
Q

What is the formula “v = f x [lambda] “ used for?

A

Calculating the speed, frequency, or wavelength of a wave.

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16
Q

What is a “radio wave”?

A

Radio waves have the longest wavelength and lowest frequency of all the waves in the EM spectrum.

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17
Q

Which waves have the longest wavelength in the EM spectrum?

A

Radio Waves

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18
Q

Which waves have the lowest frequency in the EM spectrum?

A

Radio Waves

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19
Q

What is a detector of radio waves?

A

An aerial/antenna

20
Q

What speed to EM waves travel at?

A

All EM waves travel at the speed of light (3.0x10^8ms^-1)

21
Q

What is “diffraction”?

A

When waves spread out around an obstacle this is called diffraction. Waves with longer wavelengths diffract more.

22
Q

How can diffraction affect reception in hilly areas?

A

Longer wavelength, lower frequency radio waves diffract more than higher frequency, shorter wavelengths. This means longer waves can be picked up more easily in hilly areas.

23
Q

What are “microwaves”?

A

Microwaves are part of the EM spectrum. They have a frequency of about 10GHz.

24
Q

What are some sources of microwaves?

A
  • Radar guns (police)
  • Microwave oven containing a magnetron
  • Mobile phone circuits (transmitted using aerial)
25
Q

What are some detectors of microwaves?

A
  • Mobile phone aerial

* Electronic semiconductor diode in detection circuits

26
Q

What are some dangers of microwaves?

A
  • Microwaves can cook you if the intensity is high

* Cataracts

27
Q

What is “infrared radiation”?

A

Infrared radiation is an EM wave. This type of radiation is also called heat rays. It’s invisible to the human eye.

28
Q

What are some uses of infrared radiation?

A
  • Thermal images - police use to detect criminals at night (night vision), used in airports to detect sick travellers
  • TV remotes
29
Q

What are some detectors of infrared radiation?

A
  • Thermal imaging camera
  • Semiconductor diode
  • Black bulb thermometer (black colours absorb more infrared)
30
Q

What is “visible light”?

A

Visible light are the only waves from the EM spectrum we can see. You can see objects if it emits/reflects light.

31
Q

What are some sources of visible light?

A
  • The sun
  • Light bulb
  • Fire
  • Bio-luminescents (animals that give off light)
  • Chemical reactions (e.g. Glow sticks)
32
Q

What is the “visible spectrum”?

A 
This is the colours in order of wavelength (from longest to shortest)
• Red
• Orange
• Yellow
• Green
• Blue
• Indigo
• Violet
33
Q

What is “refraction”?

A

Refraction occurs when the speed of light in glass is less that in air, so the light changes direction. This is what causes white light to split into the spectrum when it enters a glass prism.

34
Q

What is “ultraviolet light”?

A

Ultraviolet light is an EM wave with higher frequency compared to visible light.

35
Q

What are some sources of ultraviolet light?

A
  • The sun (natural)

* Sunbeds (artificial)

36
Q

What are some dangers of ultraviolet light?

A
  • Sun burn
  • Skin cancer
  • Damage to eyes
37
Q

What are some uses of ultraviolet light?

A
  • UV can make security markings on money glow
  • UV can make optical brightness in soap powder glow (fluoresce)
  • Kills bacteria and viruses. This can be used to treat water before drinking
  • Treat jaundice in new born babies
38
Q

How is ultraviolet light detected?

A

Detectors of UV are based on the fact that it can cause fluorescence.

39
Q

What are “x-rays”?

A

X-rays are the second highest frequency EM wave.

40
Q

What are some sources of x-rays?

A
  • Hospital x-ray machine (electrons fired at a metal plate)

* Energetic events in space

41
Q

What are some uses of x-rays?

A
  • Medical imaging (broken bones)
  • Airports produce images of suitcases and baggage
  • Kill cancer cells by directing beams of x-rays (or Gamma) at a tumor
42
Q

What are some dangers of x-rays?

A

Exposure to x-rays can damage or kill healthy cells and even lead to cancer.

43
Q

What are some detectors of x-rays?

A
  • Photographic film (this darkens on exposure to x-rays)

* More modern detectors use semiconductor materials

44
Q

What are “gamma rays”?

A

Gamma rays have the highest frequency and energy of the EM spectrum. It also has the shortest wavelength if all the EM waves.

45
Q

What are some sources of gamma rays?

A
  • Supernova (cosmic radiation)
  • Particle accelerators
  • Radioactive materials (e.g. nuclear fuel)
46
Q

What are some uses of gamma rays?

A
  • Kills cancer cells

* Sterilising medical equipment

47
Q

What are some detectors of gamma rays?

A
  • Geiger Muller tube and rate meter

* Photographic film - like x-rays, gamma blackens it

N5 Physics (3 decks)

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