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IGCSE PHYSICS > Unit 6 - Waves > Flashcards

Unit 6 - Waves Flashcards

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1
Q

Unit of measure for frequency

A

Hertz (Hz)

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2
Q

Longitudinal waves

A

The vibrations are parallel to the direction of travel.

Eg sound waves

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3
Q

Transverse waves

A

The vibrations are perpendicular to the direction of travel

Eg light waves, surface water waves

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4
Q

What is amplitude

A

Amplitude is the height (or depth) of the crest measured from the midpoint
More amplitude = louder sound

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5
Q

What is frequency

A

Frequency is the number of waves passing a point each second
Measured in Hz
Higher frequency = higher pitched sound

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6
Q

What is the wavelength

A 
The distance (in meters) from one waves crest to the next waves crest. 
Measured in λ (lambda)
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7
Q

What is the period of a wave

A

Time period of a wave is the time taken for one complete wave to pass (bottom to top to bottom)
Measured in seconds

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8
Q

Wave speed (m/s) =

A

Wave speed (m/s) = frequency (Hz) X wavelength (m)

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9
Q

How do waves transfer energy

A

Waves transfer energy without transferring matter

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10
Q

Time period (s) =

A

Time period (s) = 1 / frequency (Hz)

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11
Q

What is diffraction

A

When waves meet a gap in a barrier, they carry on through the gap. However the waves spread out to some extent into the area beyond the gap. This is diffraction
The extent of diffraction depends on the wavelength and physical properties of the gap

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12
Q

What can cause as wave to diffract

A

Passing through a gap

Pass an edge

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13
Q

Properties of light waves

A

Transverse wave

Can be reflected, refracted, and diffracted

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14
Q

Law of reflection

A

Angle of incidence (coming into the normal) equals the angle of reflection (leaving the normal)

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15
Q

What is rarefaction

A

Refraction is the bending of light when it enters a material of a different density.
Light refracts towards the normal when entering a higher density and away from the normal when entering a lower density.

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16
Q

What is the angle of incidence

A

The angle at which the light enters the material

measured from the normal

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17
Q

What is the angle of refraction

A

The angle that the light travels at once it has entered the new material
measured from the normal

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18
Q

What is the refractive index

A

The ratio of the velocity of light in a vacuum to its velocity in a specified medium (object)

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19
Q

Equation for refractive index

A

n = sin(i) / sin(r)
i is the angle of incidence
r is the angle of refraction

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20
Q

What is total internal reflection

A

Total internal reflection is the complete reflection of a light ray inside a Perspex wire

21
Q

Describe the role of total internal reflection in transmitting information along optical fibres

A

Behind the critical angle, light will be reflected back into the medium they came from at the same angle. In this way they are trapped in the medium. You can use this to send information down optical fibres

22
Q

What is the critical angle (c)

A

Once the angle of incidence reaches a certain point, the light will simply be refracted back into the medium. This point is the critical angle

23
Q

Equation for critical angle

A

Sin(c) = 1 / n
n is the refractive index
c is the critical angle

24
Q

Properties of sound waves

A

Longitudinal waves

can be reflected, refracted, and diffracted

25
Q

What is light

A

Light is a part of a single electromagnetic spectrum
This includes radio, microwave, infrared, visible, X-ray, ultra violet and gamma rays
All of these travel at the same speed

26
Q

The order of the electromagnetic spectrum starting at the highest frequency and decreasing

A

Gamma ray, X-ray, ultraviolet, visible, infrared, microwave, radio

27
Q

The order of the electromagnetic spectrum starting from the smallest wavelength and increasing

A

Gamma ray, X-ray, ultraviolet, visible, infrared, microwave, radio

28
Q

Uses of radio waves

A

Broadcasting and communications

29
Q

Uses of microwaves

A

Cooking and satellite transmissions

30
Q

Uses of infrared

A

Heaters and night vision equipment

31
Q

Uses of visible light

A

Optical fibres and photography

32
Q

Uses of ultraviolet light

A

Fluorescent lamps

33
Q

Uses of X-rays

A

Observing the internal structure of objects and materials and medical applications

34
Q

Uses of gamma rays

A

Sterilising food and medical equipment

35
Q

Detrimental effects of excessive exposure to microwaves and how to prevent it

A

Internal heating of body tissue

Avoid it by moving further away

36
Q

Detrimental effects of excessive exposure to infrared and how to prevent it

A

Skin burns

Avoid it by wearing SPF

37
Q

Detrimental effects of excessive exposure to ultraviolet and how to prevent it

A

Damage to surface cells and blindness

Avoid it by wearing protective clothing

38
Q

Detrimental effects of excessive exposure to gamma rays and how to prevent it

A

Cancer and cell mutation

Avoid it by wearing protective clothing and increasing distance from the source

39
Q

What is meant by an analogue signal

A

An analogue signal can constantly vary in frequency and amplitude, eg a persons voice

40
Q

What is meant by a digital signal

A

A digital signal is binary and can only be a 1 or a 0, eg a modern radio signal

41
Q

What is the benefit to transmitting data in the digital format

A

All signals lose definition when transmitted and need to be amplified. When amplified, and analogue signal will remain unclear and is difficult to clarify whereas a digital signal can only be a 1 or 0 so it is easy to amplify and regain clarity

42
Q

describe experiments to investigate the refraction of light, using rectangular blocks, semicircular blocks and triangular prisms

A

Place a block of glass on a piece of paper, drawing an outline.
At one point, draw the normal line.
Draw a line at 30 degrees to the normal line, shine a ray of light down this line.
Draw a line where the light comes out the other side. Connect the two lines, drawing the refracted ray.

43
Q

describe an experiment to determine the refractive index of glass, using a glass block

A 
Shine a ray of light through a glass block, measure the angle of incidence and the angle of refraction.
Do sin(i) divided by sin(r) and you will have the refractive index of glass.
44
Q

How digital signals carry more information

A

They have a larger bandwidth

45
Q

What is the frequency range of human hearing

A

20 Hz - 20,000 Hz

46
Q

Describe an experiment to measure the speed of sound in air

A

Measure the distance between two places, have a sound made in one place, as soon as you see the sound has been made start a stop watch, as soon as you hear the sound made stop the stopwatch.

47
Q

How an oscilloscope and microphone can be used to display a sound wave

A

A microphone converts sound energy into electrical energy in the form of electronic signals. A computer or an oscilloscope can be used to display these electronic signals, which show the same changes in amplitude and frequency as the sound waves.

48
Q

Describe an experiment using an oscilloscope to determine the frequency of a sound wave

A

Have an noise made into a microphone attached to an oscilloscope, for example have someone try to sing a note. See how many oscillations there are per second, this will be your frequency. Try changing the pitch of the note and see it the number of oscillations per second changes.

IGCSE PHYSICS (8 decks)

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