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Physics > Waves > Flashcards

Waves Flashcards

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1
Q

Define frequency

A

The number of complete waves produced per second

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2
Q

Define wavelength

A

Shortest Distance between two consecutive throughs or crests or any two points in phase

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3
Q

Define period

A

Time taken for one complete wave to be produced

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4
Q

Define amplitude

A

Maximum displacement of wave from rest/equillibrium position

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5
Q

Define “in phase”

A

Any two points on a wave that have the same displacement from rest position and moving in the same direction

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6
Q

Define wavefront

A

An imaginary line on the wave that connects all adjacent points that are in phase.

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7
Q

What are longitudinal waves?

A

Longitudinal waves are waves which travel in a direction parallel to the vibration of particles

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8
Q

What are transverse waves?

A

Transverse waves are wave which travel in a direction perpendicular to the vibration of particles

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9
Q

What property of soundwaves relates to loudness?

A

Amplitude

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10
Q

What property of soundwaves relates to pitch?

A

Frequency

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11
Q

What are some uses of ultrasound?

A
  • Prenatal Scanning
  • Quality Control (checking for cracks in concrete slabs)
  • Sonar Technologies
  • Breaking up kidney stones and cancer treatment
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12
Q

Formula for speed of a wave

A

v = f (frequency) x λ (wavelength)

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13
Q

Formula for frequency

A

f = 1/T (period)

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14
Q

How is sound created?

A

It is created because of the particles vibrating to and fro about equillibrium position. The Particles collide with neigbouring particles causing it to vibrate therefore transferring energy. The vibration of air particles spread outwards from source in a series of rarefactions and compressions propagating as soundwaves

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15
Q

List all EM waves from lowest frequency to highest frequency.

A

radio waves, microwaves, infrared, visible light, ultraviolet , X-ray, gamma ray

Remember: Ronald McDonald Is Very Understanding To Everyone Except Girls

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16
Q

What is the speed of light in a vacuum?

A

3×10^8 m/s

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17
Q

Define refraction.

A

Refraction is the bending of light ,due to a change in speed of light, as light passes from one optical medium to another

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18
Q

Formula for refractive index (n)

A
  • sin i (larger angle) / sin r (smaller angle)
  • speed of light in a vacuum / speed of light in medium
  • real depth / apparent depth
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19
Q

What are the characteristics of an image made by
plane mirror?

A
  • virtual
  • upright
  • laterally inverted
  • same size as object
  • Object distance from mirror is same as image distance from mirror
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20
Q

How does total internal reflection occur?

A
  • Light rays travel from an optically denser medium to the boundary of an ptically less dense medium
  • Angle of incidence in the denser medium is greater than the critical angle
21
Q

Define critical angle

A

Critical angle is the angle of incidence in the optically denser medium where the an angle of refraction in the optically less dense medium is 90°.

22
Q

Formula for critical angle

A

sin c = 1 / n (refractive index)

23
Q

State the 2 laws of reflection

A
  1. The incident ray, the reflected ray and the normal all lie on the same plane.
  2. The angle of incidence is equal to the angle of reflection.
24
Q

State an application of total internal refraction

A

optical fibres in telecommunication

25
Q

State advantages of using an optical fibre instead of copper wires.

A
  • less signal degradation
  • light weight
  • lower costs
26
Q

Light will bend away from normal when…

A

light travels from an optically denser medium to an optically less dense medium

27
Q

Define focal length.

A

Focal length is the distance between the centre of the lens and the focal point.

28
Q

Define focal point.

A

The focal point is a point where a parallel beam of light will converge at after passing through the lens.

29
Q

As an object mover nearer to the lens,…

A

image will move away from lens.

30
Q

As image moves away from lens,…

A

size of image increases.

31
Q

How would an increase in refractive index in glass affect focal length?

A
  • Focal length would be shorter
  • Light would bend more towards normal when entering glass.
  • Light would bend more away from normal when exiting glass
32
Q

Uses of Radiowaves

A

used in radio and television communications, astronomy and Radio Frequency Identification (RFID) tag

33
Q

Uses of Microwaves

A

used in cooking in microwave oven, satellite television, mobile phones signals, radar (radio detection and ranging), cancer treatment, WIFI signals and Global Positioning System (GPS). (Note: Microwaves is responsible for satellite communication not radio waves, as microwaves can
penerate through the atmosphere but radio waves cannot.)

34
Q

Uses of Infrared Radiation

A

used in cooking or keeping warm, infra-red remote controllers, infrared thermometers and thermal imaging, intruder alarms, short range data transfer (between devices like mobile phone and laptops) and camera auto-focusing. Also, greenhouses are used to trap infrared (to maintain a warm interior for plants).

35
Q

Uses of visible light

A

used in photography and photographic film, optical fibres for telecommunications (data transfer) and for medical uses (eg. endoscope), artificial lights for plant growth, and for hardening and curing of materials

36
Q

Uses of Ultraviolet Rays

A

used in disinfection and sterilization (eg in water treatment), sunbeds (vitamin D production to produce vitamin D in our body) and anti-forgery features (eg. bank note authentication).

37
Q

Uses of X-rays

A

used in disinfection and sterilization, medical radiology (X-ray imaging and Computed Tomography (CT scan)), security screening to scan luggages and industrial defect detection to scan for defects/cracks.

38
Q

Uses of gamma rays

A

(the most energetic waves) - used in disinfection and sterilization of food,
radiotherapy to kill cancer cells and quality control in manufacturing.

39
Q

What is properties of image when u (object distance) = ∞

A
  • Inverted
  • Real
  • Diminished
  • Image distance = f
  • Opposite side of Lens
  • lens of telescope
40
Q

What is properties of image when u (object distance) > 2f

A
  • Inverted
  • Real
  • Diminished
  • f < image distance < 2f
  • Opposited side of Lens
  • camera
41
Q

What is properties of image when u (object distance) = 2f

A
  • Inverted
  • Real
  • Same Size
  • Opposite side of Lens
  • Image distance = 2f
  • Photocopier
42
Q

What is properties of image when f < u (object distance) < 2f

A
  • Inverted
  • Real
  • Magnified
  • Opposite side of Lens
  • Image distance > 2f
  • Projector
43
Q

What is properties of image when u (object distance) = f

A
  • Upright
  • Virtual
  • Magnified
  • Image distance = ∞
  • Same side of lens
  • Spotlight
44
Q

What is properties of image when u (object distance) < f ?

A
  • Upright
  • Virtual
  • Magnified
  • Same side of lens
  • image is behind object
  • Magnifying Glass
45
Q

Why cant the formula for critical angle (sin θ =1/n) be used anywhere?

A

Formula can only be used when light travels from a optically dense medium to air.

46
Q

Define total internal reflection

A

Total internal reflection is the complete reflection of a light ray in an optically denser medium at the boundary with an optically less dense medium

47
Q

Harmful effects of exposure of UV rays

A

Heating – sunburn (cause by too much UV exposure), frequent sunburns can cause premature skin aging and higher risk of skin cancer.

48
Q

Harmful effects of Ionising Radiation. (UV, X-Ray, Gamma rays)

A

Ionising waves have higher frequencies and hence higher energies. They can eject electrons from atoms and molecules to create ions. These ions can cause harm by disrupting cell functions and even killing them. This can lead to cell death or mutations leading to diseases and organ failure.

Physics (7 decks)

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