Waves Flashcards

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1
Q

Difference between longitudinal and transverse waves

A

Longitudinal : travel parallel to the direction of travel
Transverse : travel perpendicular to the direction of travel

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2
Q

What is amplitude

A

The distance from the centre lin to the peak or trough of a wave

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3
Q

What is frequency

A

The number of waves passing a certain point in a specific amount of time

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4
Q

What is wavelength

A

The distance between two peaks

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5
Q

What is wavefront

A

An imaginary surface representing points of a wave that are in the same points of their cycle

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6
Q

What is the period of a wave

A

The time for one complete cycle

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7
Q

what do waves transfer and what do they not

A

waves transfer energy and information

they don’t transfer matter

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8
Q

what is the relationship between the speed, frequency and wavelength of a wave

A

wave speed = frequency x wavelength

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9
Q

what is the relationship between frequency and time period

A

frequency = 1/time period

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10
Q

what is the doppler effect

A

a change in the observed frequency and wavelength of a wave when its source is moving relative to an observer.

Ahead of the car wavefronts are compressed as the car is moving in the same direction as the wavefronts. This creates a shorter wavelength and a higher frequency.

Behind the car wavefronts are more spread out as the car is moving away from the previous wavefronts. This creates a longer wavelength and a lower frequency.

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11
Q

explain that all waves can be reflected and refracted

A
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12
Q

what spectrum is light part of

A

the electromagnetic spectrum

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13
Q

list the electromagnetic spectrum in order of decreasing wavelength

A

radio waves
microwaves
infrared
visible light
ultraviolet
x-rays
gamma rays

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14
Q

what are the components of visible light

A

V violet
I indigo
B blue
G green
Y yellow
O orange
R red

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15
Q

when do all waves in the EM spectrum travel at the same time

A

in free space

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16
Q

what is the use of radio waves

A

broadcasting and communicaions

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17
Q

what is the use of microwaves

A

cooking and satellite transmissions

18
Q

what is the use of infrared waves

A

heaters and night vision equipment

19
Q

what is the use of visible light

A

optical fibres and photography

20
Q

what is the use of ultraviolet waves

A

florescent lamps

21
Q

what is the use of x-rays

A

observing the internal structure of objects and materials, including medical applications

22
Q

what is the use of gamma rays

A

sterilising food and medical equipment

23
Q

explain the detrimental effects of excessive exposure of the human body to microwaves and describe a simple protective measure against it

A

internal heating of body tissue

protective measure- reduce exposure

24
Q

explain the detrimental effects of excessive exposure of the human body to infrared light and describe a simple protective measure against it

A

skin burns

protective measure- reduce exposure

25
Q

explain the detrimental effects of excessive exposure of the human body to ultraviolet and describe a simple protective measure against it

A

damage to surface cells and blindness

protective measure- reduce exposure

26
Q

explain the detrimental effects of excessive exposure of the human body to gamma rays and describe a simple protective measure against it

A

cancer, mutation

protective measure- reduce exposure

27
Q

what are light waves and what can happen to them

A

light waves are transverse waves and they can be reflected and refracted

28
Q

what is the law of reflection

A

angle of incidence = angle of reflection

29
Q

how do you draw a ray diagram to illustrate reflection

A

draw an incident ray and a normal, angle of incidence is incidence ray towards normal

draw the reflected ray and measure and angle of reflection which is ray of reflection towards normal

30
Q

how do you draw a ray diagram to illustrate refraction

A

draw an incident ray and a normal, angle of incidence is incidence ray towards normal

draw a refracted ray which is bent towards the normal and the angle of refraction is from the ray of refraction towards the normal

31
Q

what apparatus is needed to investigate the refraction of light

A

rectangular blocks
semi-circular blocks
triangular prisms

32
Q

what is the relationship between refractive index, angle of incidence and angle of refraction

A

n = sin i / sin r

33
Q

describe the practical for investigating the refraction of light

A

1) shine a ray onto one of the sides of the glass block, so that the ray emerges on the opposite side of the block. mark the directions of both these rays with crosses

2) draw around the glass block before removing it

3) using the crosses, draw in the direction of both rays

4) draw in the direction of the ray that travelled inside the glass block

5) draw a normal line where the ray enters the block

6) measure the angle of incidence and angle of refraction

7) use the equation sin i / sin r to find the refractive index of the glass block

33
Q

what is the role of TIR in transmitting information along optical fibres and in prisms

A

it is used to transmit signals along optical fibres

34
Q

explain the meaning of the critical angle c

A

The angle of incidence which produces an angle of refraction of 90 (refracted ray is along the boundary of the surface).

When the angle of incidence is greater than the critical angle, total internal reflection occurs (all light is reflected at the boundary).

This effect only occurs at a boundary from a high refractive index material to a low refractive index material.

35
Q

what is the relationship between critical angle and refractive index

A

sin c = 1/n

36
Q

what are sound waves and what can happen to them

A

they are longitudinal waves and they can be reflected and refracted

37
Q

how can oscilloscope and microphone be used to display a sound wave

A

With the microphone plugged into the oscilloscope and a sound incident on the microphone, the microphone will transfer the sound into an electrical signal which the oscilloscope can display .The x axis show the time base which can be adjusted for example 2ms for 1 square so time period and frequency can be calculated from this, along the y axis voltage is displayed as the wave is converted into an electrical signal this means amplitudes can be compared.

37
Q

what is the frequency for human hearing

A

20 hz to 20,000 hz

37
Q

describe the practical to investigate the speed of sound in air

A
38
Q

how does the loudness of a sound relates to the amplitude of vibration of the source

A

The greater the amplitude the louder the sound. Bigger vibrations of a sting mean more energy is being put in so more energy out as sound waves.

39
Q

how does the pitch of a sound relate to the frequency of vibration of the source

A

High frequency means high pitch. If a string vibrates with a higher frequency then the note sounds higher.