Waves Flashcards

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1
Q

What is a transverse wave?

A

Oscillations are perpendicular to the direction of travel

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2
Q

What is a longitudinal wave?

A

Oscillations are parallel to the direction of travel

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3
Q

What is amplitude?

A

Maximum displacement from the normal position

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4
Q

What is frequency?

A

Number of waves per second

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5
Q

What is wavelength?

A

Distance from crest to next crest

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6
Q

What is Time Period?

A

Time for wave to complete one oscillation

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7
Q

Equation: Wave speed v =

A

v = frequency x wavelength

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8
Q

Equation: Frequency f =

A

f = 1/time period
f = 1/T

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9
Q

Give an example of a longitudinal wave.

A

Sound

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10
Q

Give an example of a transverse wave.

A

Electromagnetic spectrum
Water waves

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11
Q

What is the Doppler effect?

A

When the source of a wave moves towards the observer, observed frequency increases.
When a source moves away, observed frequency decreases.

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12
Q

What do all waves do?

A

Transfer energy and information without transferring matter.

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13
Q

List the electromagnetic spectrum in order of decreasing wavelength and increasing frequency.

A

Radio
Microwaves
Infra Red
Visible Light (ROYGBIV)
Ultra violet
X Rays
Gamma rays

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14
Q

Give a use and hazard of gamma rays?

A

use: sterilising food and medical equipment
hazard: cancer and cell mutations

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15
Q

Give a use and hazard of X rays?

A

use: observing internal structures like bones
hazards: cancer and cell mutations

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16
Q

Give a use and hazard of ultra violet.

A

use: fluorescent lamps, tanning lamps, checking counterfeit money
hazards: damage tovsurface cells of the skin and blindness

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17
Q

Give a use and hazard of infra red.

A

use: heaters and night vision
hazards: skin burns

18
Q

Give a use and hazard of microwaves.

A

use: cooking and satellite communications/moblie phones
hazards: internal heating of body tissues

19
Q

Give a use of visible light.

A

photography

20
Q

Give a use of radio waves.

A

broadcasting and communications
radar

21
Q

What properties do all electromagnetic waves have in common?

A

all transverse waves
all travel in a vacuum
all travel at same speed in a vacuum (300 000 000m/s)

22
Q

What is the Law of reflection?

A

Angle of incidence = angle of reflection

23
Q

What must you remember when measuring the angles of incidence and reflection?

A

measured between the ray and the normal

24
Q

Equation for refective index n =

A

n = sin i/ sin r

25
Q

What are the 2 conditions for Total internal reflection to occur?

A
  1. Ray travelling from a higher refractive index to a lower refractive index
  2. at an angle greater than the critical angle
26
Q

What is the critical angle?

A

Angle at which the ray refracts at 90 degrees along the boundary. Angle greater than critical and total internal reflection occurs.

27
Q

For critical angle c sin c =

A

sin c = 1 / n

28
Q

Refraction is the change of direction of a wave what changing speed.
Travelling from less optically dense to more optically dense medium, what happens to speed, wavelength and frequency?

A

less dense to more dense:
speed decreases
wavelength decreases
frequency stays the same

29
Q

Refraction is the change of direction of a wave what changing speed.
Travelling from more optically dense to less optically dense medium, what happens to speed, wavelength and frequency?

A

more dense to less dense:
speed increases
wavelength increases
frequency stays the same

30
Q

What is the frequency for human hearing?

A

20 to 20 000 Hz

31
Q

Pitch of sound is related to ….

A

frequency

32
Q

Loudness of sound is related to ….

A

amplitude

33
Q

What equipment do we use to investigate sound waves?

A

mircrophone connected to an oscilloscope

34
Q

What equipment do we need to investigate speed of sound?

A

Two microphones 2 m apart
Make sound with hammer
First microphone starts timer
Second timer stops microphone
Repeat and find an average
Speed = distance / time

35
Q

What is a wavefront?

A

Line of points in phase with each other (move together)

36
Q

Waves transfer energy and information without ….

A

transferring matter.

37
Q

Is light longitudinal or transverse?

A

transverse

38
Q

Is sound longitudinal or transverse?

A

longitudinal

39
Q

Name two uses of total internal reflection

A

fibre optics in cable tv and endoscopes
prism binoculars

40
Q

All waves can be …..

A

All waves can be reflected and refracted