1
Q
what is a transverse wave
A
A wave where the oscillations/ vibrations are perpendicular to the direction of energy transfer
2
Q
what is a longitudinal wave
A
the vibrations of longitudinal waves are parallel to the direction of energy transfer
3
Q
draw longitudinal and transverse waves
A
🌊
3
Q
What is the amplitude of a wave
A
-maximum disturbance
-1/2 distance of peak to trough
4
Q
what is the wave front
A
the middle line on which every wave passes through
5
Q
what is the frequency of a wave
A
number of waves created every second
6
Q
what is the wavelength
A
the distance between one peak of the wave to another
7
Q
what is the time period of a wave
A
time it takes for one wave to pass, measured in seconds
8
Q
what are three examples of transverse waves
A
radio waves, light waves, ripple on the surface of water
9
Q
what are three examples of longitudinal waves
A
shock waves, sound waves, seismic waves
10
Q
what do waves transfer and what done they transfer
A
they transfer energy and information without transferring matter
11
Q
what is the relationship between wave speed, frequency and wavelength
A
wave speed = frequency x wavelength or v= f x lambda
12
Q
what is wave speed measured in
A
m/s
13
Q
what is frequency measured in
A
Hz
14
Q
what is the wavelength measured in
A
metres, m
15
Q
what is the relationship between frequency and time period
A
frequency= 1/time period or f=1/t
16
Q
do questions with the frequency and wave speed equations
A
17
Q
what is the doppler effect
A
when a moving object creates a sound, the pitch of the wave changes. This is because the wavelength and frequency of the wave changes but the speed of the wave is unchanged
18
Q
what happens in the doppler effect if the object moves towards you
A
-speed remains constant, wavelength decreases and frequency increases. Pitch is higher
19
Q
what happens in the doppler effect if the object is moving away from you
A
-speed remains constant, wavelength increases and frequency decreases. the pitch gets lower
20
Q
what is the frequency range for human hearing
A
20-20,000 Hz
21
Q
how does the frequency of a wave affect the pitch
A
the higher the frequency, the higher the pitch and vice versa
22
Q
what is reflection
A
the law of reflection states that the angle of incidence=the angle of reflection. when a (light) wave hits a surface and bounces back into the original medium.
23
Q
what can all waves do
A
be reflected and refracted
24
what is refraction
refraction is when light (waves) changes speed as it enters a new medium as the medium has a different optical density
25
what light waves are part of the electromagnetic spectrum and what is their speed
radio, microwave, infrared, visible, ultraviolet, x-ray and gamma ray
-all of these waves travel at the same speed in free space
26
what is the speed of light
3 x 10^8 m/s
27
what are the EM waves in order of wavelength from high to low and frequency from low to high
radio, microwave, infrared, visible, ultraviolet, x-ray, gamma ray
28
what are the uses of radio waves
broadcasting and communications
29
how do radio waves work
they spread out as they pass over large buildings and hill. The longer length radio waves are reflected off the earth's outer atmosphere
30
what are the uses of microwaves
satellite and cooking
31
how do microwaves work in satellites
they can carry more information than radio waves and are able to pass through the atmosphere to reach the satellites
32
how do microwaves work in cooking
-water is very good at absorbing microwaves
-food containing water will absorb the energy of microwaves causing them to be heated
-some of the microwaves will penetrate into the food causing the inside to be heated
33
what are the dangers of microwaves
as people contain a lot of water there could be a internal heating of body tissue-dont go in microwave
34
what are the uses of infrared waves
-cooking and thermal imaging
35
how does thermal imaging use infrared waves
-all objects emit infrared radiation so using a thermal imaging camera you can see them
36
how can infrared be used for cooking
-grills and heat transfer heat by infrared radiation
-the surface of the food will absorb the energy of the infrared waves, causing heating at the surface
37
what are the dangers of infrared radiation
if too much is absorbed in your skin it can cause skin burns-dont touch grills
38
what are the uses of visible light
optical fibres and endoscope
39
how do optical fibres use visible light
-optical fibres send signal using visible light waves (and infrared)
40
how do endoscopes use visible light
-an endoscope can be used to see deep inside your body
-light is reflected along optical fibres back to a camera
41
what are the uses of ultraviolet light
fluorescence (and tanning)
42
how does fluorescence use ultraviolet light
fluorescent materials absorb ultraviolet and emit the energy as visible light. this can be used in lightings and security markings
43
what are the dangers of ultraviolet light
-exposure to UV light can lead the skin to tan and the darkening skin helps to protect it
-too much exposure can lead to sunburn where you are damaging your skin's surface cells-wear suncream
-ultraviolet light can also cause blindness-wear sunglasses
44
what are the uses of x-rays and how does it work
-x rays can be used to observe the internal structure of object such as inside living animals
-x rays are absorbed by bone and are transmitted through soft tissue
-the photographic film turns black when they are exposed to x rays
-the photographic film will remain white in regions that are not exposed to x rays-places where bone is
45
what are the uses of gamma rays and how do they work
-gamma rays can be used to sterilise food and surgical equipment by killing the microbes that live on them
46
what are the dangers of gamma rays and how can they be prevented
-UV, x-rays and gamma rays are types of ionising radiation
-they can ionise atoms and molecules
-if these molecules are part of living cells, the cell can be damaged, mutated (cause cancer) or be destroyed
-this can be prevented by reducing exposure or wearing a lead shield
47
what type of waves are light waves
transverse waves which can be refracted and reflected
48
what types of waves are sound waves
longitudinal waves which can be refracted and reflected
49
what is the refractive index
a measure of how quickly the light will travel in a medium compared to in a vacuum or air it is a ratio
50
what is the relationship between the refractive index, angle of incidence and angle or refraction
refractive index= sin(angle of incidence)/ sin(angle of refraction) or n= sin(i)/ sin(r)
51
draw ray diagrams of reflection and refraction
👩🔬
52
what is total internal reflection
when all light is reflected at a boundary (that is not air first) and remains in the non-air medium. No refraction occurs
53
what happens when a ray of light enters a rectangular glass block
-the ray of light bends towards the normal
-this is due to refraction
-this is because the light enters a more dense medium and the light slows down
54
what are the condition needed for total internal reflection
1, angle of incidence must be greater than critical angle
2. the light must be travelling from high refractive index to low refractive index e.g glass to air not air to glass
55
what happens to a wave as it travels from deep to shallow water
-wave speed is high in deep water
-when it travels to shallow water, wave speed gets lower and wavelength decrease due to wave speed=frequency x wavelength and the frequency remains constant
-there is also a change in direction as when the wave slows down the direction of energy transfer bends towards the normal
56
draw TIR diagram
57
define the critical angle
the angle of incidence that causes the angle of refraction to=90 degrees
58
how does the colour of light affect the refractive index of a materials
-the colours of light refract by different amounts as light travels at different speeds depending on their colour (or wavelength)
-violet light slows down more than red light
-we see this because there is a greater change of direction when the light bends towards the normal
-this means that the refractive index for violet light is slightly higher than for red light as it has a smaller angle of refraction and bends more towards the normal
59
how do optical fibres use TIR
-optical fibres
-light is transmitted in a piece of glass where the angle of incidence is larger than the critical angle so it continues reflectin
it is used in medicine for endoscopes and broadband internet services
60
what are two uses of TIR
-optical fibres
-cats eyes
61
how do cats eyes use TIR
-prisms of glass embedded into the road
-The light from the headlamps TIR back to the car
62
what is the relationship between the critical angle and the refractive index
sin(critical angle) = 1/ refractive index or sin(c)=1/n
63
what piece of apparatus can be connected to an oscilloscope to detect ultrasound waves
microphone
64
what are the three main parts of an oscilloscope and what are their roles
-screen: shows image of the signal
-time base: tells us the scale of the x-axis on the screen-how many milliseconds per square
-y-gain (volts/div): tells us scale of the y axis-how many volts per square
65
How do you work out the frequency from an oscilloscope
-work out the time period
-frequency=1/time period converted into seconds e.g 1/ 8x10^-3
66
how do you work out the amplitude on an oscilloscope
1.read the height of the wave off the y-axis
or
2. count the squares up from the middle line to top of the wave then multiply by y-gain e.g 2x2volts=4 volts
67
do oscilloscope questions
68
how do you calculate the time period on an oscilloscope (3 marks)
-adjust oscilloscope so 1 or more waves are seen on the screen
-count the squares from peak to peak of a wave
-multiply number of squares by time base
69
how can you improve the accuracy of a time period measurement on a oscilloscope
-adjust oscilloscope so more waves are seen on the screen rather than 1
-divide by the number of waves after calculating the time period
70
how does the volume of a sound relate to the amplitude of a wave
higher amplitude means higher volume, lower amplitude means lower volume
71
What type of image is formed by a mirror
Virtual
72
What is the method of core prac 5: investigating the refractive index of glass
1. Before turning off the lights, place the glass block in the middle of the plain piece of paper and draw around it using a pencil, then turn off the lights
2. Align the ray box so a single beam of light is incident on one surface of the glass block
3. Observe the path of the light and using a pencil, trace over the light travelling into and out of the block onto the plain paper
4. Remove the glass block from the piece of paper and using a ruler, join up the two lines that you have drawn with a single straight pencil line
5. At the point where the incident ray reaches the glass block, draw a normal to the surface of the glass block using a protractor
6. Measure the angle of incidence and angle of refraction using a protractor and record results
7. Repeat steps for seven values of angle of incidence and refraction
8. Calculate sin(i) and sin(r) for each measure to and then plot on a graph with sin(i) on the y axis and sin(r) on the x axis
9. For the refractive index, calculate the gradient
73
In core prac 5: investigating the refractive index of glass, why is it important to make the beam of light as thin as possible
So that the angle can be as accurate and precise as possible so the line can point to a specific and precise angle instead of a range
74
What is the method of core prac 6: investigating the speed of sound
1. Stand between 100-200m from your partner, ensuring that you measure this distance using a long measuring tape or trundle wheel. Record the distance in the results table
2. When ready, one student should raise the wooden blocks or hinged clapper board above their head ready to make a loud sound
3. The other student should be ready and watching. Start the stop clock when you observe the students banging the wooden blocks together and stop it when you hear the sound and record the time in the results table
4. Repeat the whole experiment at least 4 times
75
In core prac 6: investigating the speed of sound how can reliability be increase
Repeat the experiment and calculate a mean/average which removes random errors
76
In core prac 6: investigating the speed of sound what assumption is made
That the speed of light is much faster than the speed of sound
77
In core prac 6: investigating the speed of sound why is a larger distance between the students more effective
Increases the accuracy of measurements as if there is a small error in reaction time it will not affect the results as much
