P5 Flashcards
(120 cards)
1
Q
What is a wave?
A
A wave is an oscillation that transfers energy.
2
Q
What are the two main types of mechanical waves?
A
Transverse waves and longitudinal waves.
3
Q
What is the direction of vibration in longitudinal waves?
A
The direction of vibration is the same as the direction of the wave.
4
Q
What is the direction of vibration in transverse waves?
A
The direction of vibration is at right angles to the direction of travel of the wave.
5
Q
What are the properties of waves?
A
Amplitude, wavelength, frequency, and period.
6
Q
What is amplitude?
A
The distance from the middle to the top (crest) or bottom (trough) of a wave.
7
Q
What is wavelength?
A
The distance from one point on a wave to the same point on the next wave.
8
Q
What is frequency?
A
The number of waves, or oscillations, per second.
9
Q
What is the time period of a wave?
A
The time for one wave to pass a given point.
10
Q
What is wave velocity?
A
The speed at which the wave travels through the medium.
11
Q
How can you model transverse waves?
A
Using ripples on water surfaces.
12
Q
What happens to the water when a wave travels through it?
A
The wave travels but the water does not.
13
Q
How can you measure the wavelength on a time trace?
A
Measure from any point on a wave to the same point on the next wave.
14
Q
How can you measure the amplitude of a wave?
A
From the middle to the top (crest) or bottom (trough) of a wave.
15
Q
What is the unit for frequency?
A
Hertz (Hz).
16
Q
What is the unit for wavelength?
A
Metres (m).
17
Q
What is the unit for time period?
A
Seconds (s).
18
Q
What is the significance of the x-axis on a wave graph?
A
It indicates whether you can find wavelength or time period from the graph.
19
Q
What should you be able to describe and apply after studying wave velocity?
A
The relationship between frequency, wavelength, and wave velocity.
20
Q
What formula relates wave velocity, frequency, and wavelength?
A
wave velocity (m/s) = frequency (Hz) × wavelength (m)
21
Q
How do you measure the speed of ripples on water surfaces?
A
By knowing the frequency of the ripples and their wavelength.
22
Q
How do you measure the speed of sound?
A
By timing how long it takes to hear an echo of a clap.
23
Q
What is the unit of frequency?
A
1 Hz = 1 wave per second.
24
Q
What happens to the wavelength if the frequency increases?
A
The wavelength decreases.
25
What is the velocity of sound in air at 25°C?
340 m/s.
26
What is the velocity of sound in water?
1500 m/s.
27
What is the velocity of sound in steel?
500 m/s.
28
How does temperature affect the velocity of sound?
The velocity of sound increases with temperature.
29
How can you calculate the wavelength if you know the frequency and velocity?
Rearrange the formula: wavelength = wave velocity / frequency.
30
What is the velocity of a tidal wave that can cross the Atlantic in about 8 hours?
600 mph.
31
How can you visualize wave velocity using running?
Your stride represents the wavelength and strides per second represent frequency.
32
What happens to the sound wave trace on an oscilloscope?
It shows the variation of pressure with time, not the sound wave itself.
33
What equipment can be used to measure the velocity of sound in a liquid or solid?
A pair of microphones connected to an oscilloscope.
34
What should you be able to describe after studying sound properties?
You should be able to describe changes in velocity, frequency, and wavelength when sound waves move from one medium to another, as well as the effects of reflection, transmission, and absorption of sound waves at the boundary between two materials.
35
What happens when sound travels across a boundary?
When a wave travels from one medium to another, its velocity and direction can change, which is known as refraction.
36
What happens to the frequency of a sound wave when it travels faster and its wavelength increases?
The frequency stays the same.
37
What are the three things that can happen when a sound wave hits a boundary?
The sound can be reflected, transmitted (and possibly refracted), or absorbed.
38
What is ultrasound?
Ultrasound is sound of a frequency greater than 20000 Hz, which cannot be heard by humans but can be heard by many animals.
39
Why is ultrasound useful?
Ultrasound has a very small wavelength, allowing it to be focused into a beam.
40
How do doctors use ultrasound?
Doctors use ultrasound to create images, find kidney stones, and monitor blood flow by sending ultrasound waves that reflect from different boundaries.
41
What is echo-sounding and sonar?
Echo-sounding and sonar use the time for an echo and the speed of sound in water to find distances.
42
What should you consider when determining what happens to waves at a boundary?
Look carefully to see if they are speeding up or slowing down.
43
What happens to a sound wave that travels from a liquid into a solid?
The properties of the sound wave change, typically resulting in increased speed and possibly a change in direction.
44
What should you be able to describe after studying sound in solids and the ear?
You should be able to describe processes that convert wave disturbances between sound waves and vibrations in solids, such as in the human ear.
45
Why do sound wave processes work only over a limited frequency range?
This is related to human hearing.
46
What are the ossicles in your ear?
The ossicles are the only bones in the body that do not grow; they are the same size as when you were born.
47
What happens when a sound wave hits a solid?
The sound is eventually absorbed after being reflected many times, making the particles in the wall vibrate and causing the wall to get a bit hotter.
48
What does a microphone do when it absorbs a sound wave?
It produces a changing electrical signal.
49
How does your ear detect sound?
Your ear is designed to detect, amplify, and convert sound to an electrical signal.
50
What is the role of the outer ear?
The outer ear (pinna and auditory canal) gathers the sound wave and directs it to the ear drum, which vibrates.
51
What happens when the ear drum vibrates?
It makes the ossicles vibrate, amplifying the vibration and passing it on to the inner ear through the oval window.
52
What is the cochlea and its function?
The cochlea is shaped like a snail shell and contains fluid that transmits the movements of the oval window to small hairs on the inside wall, which release chemical substances to send signals to the brain.
53
Why do you hear only a particular range of frequencies?
Objects that can vibrate, like hairs in your cochlea, have a natural frequency, and they resonate at different frequencies of sound.
54
What happens as you get older regarding hearing?
You lose the shorter hairs in your cochlea, making it more difficult to hear higher frequencies.
55
What can affect the range of frequencies you hear as you age?
Listening to loud music can affect your hearing range or damage your hearing.
56
What is the significance of the 'R' in MRI scanning?
The 'R' stands for 'resonance'.
57
What are some uses of electromagnetic waves in communication?
Electromagnetic waves are used in communication through microwaves for mobile phones, WiFi, and Bluetooth; radio waves for TV and radio signals; infrared for remote controls; and visible light for communication using flashing signals and Morse code.
58
How do microwaves work in a microwave oven?
In a microwave oven, water and fat in food absorb microwaves, heating the outside of the food, while conduction transfers energy to the middle.
59
What is the role of infrared radiation in cooking?
Infrared radiation cooks food in a grill or oven and can also heat you through a radiator.
60
What is the benefit of ultraviolet radiation?
Ultraviolet radiation helps produce vitamin D, which is essential for strong bones.
61
How is ultraviolet radiation used in forensic science?
Forensic scientists use ultraviolet light to detect bodily fluids, as they glow under UV light.
62
What are the dangers of ultraviolet radiation?
Ultraviolet radiation can damage DNA in skin cells, leading to skin cancer, and can cause cataracts in the eyes.
63
What are the dangers of X-rays?
X-rays can damage cells and increase the risk of cancer, which is why radiographers use protective measures.
64
What are the dangers of gamma rays?
Gamma rays can damage or kill cells in the body, posing health risks.
65
Why is using X-rays on your feet to see if your shoes fit a bad idea?
Using X-rays on your feet is a bad idea because X-rays can damage cells and increase cancer risk.
66
What concerns do some scientists have about mobile phone use?
Some scientists believe that using mobile phones may affect health due to potential radiation exposure.
67
What is the relationship between the number of uses of microwaves and the microwave region of the electromagnetic spectrum?
The number of uses of microwaves corresponds to their specific region in the electromagnetic spectrum, which is utilized for various communication technologies.
68
Which stores more information: a Blu-ray Disc or a CD that uses red laser light?
A Blu-ray Disc stores more information than a CD because it uses a blue laser, which has a shorter wavelength, allowing for more data to be packed into the same physical space.
69
What are electromagnetic waves?
Electromagnetic waves consist of oscillating electric and magnetic fields.
70
What is the speed of electromagnetic waves in a vacuum?
All electromagnetic waves travel through a vacuum at 3.0 x 10^8 m/s.
71
What is the range of frequencies our eyes detect?
Our eyes are sensitive to a narrow range of frequencies called visible light.
72
What are the main groupings of the electromagnetic spectrum?
The main groupings include radio waves, microwaves, infrared (IR), visible light, ultraviolet (UV), X-rays, and gamma rays.
73
How are radio waves produced?
An oscillating potential difference across a wire makes electrons move, producing a changing electric and magnetic field.
74
How are radio waves detected?
When the changing fields meet another piece of metal, such as an aerial, it causes electrons to move, producing an electrical signal.
75
What is the relationship between speed, frequency, and wavelength for electromagnetic waves?
The relationship is given by the formula: wave speed = frequency × wavelength.
76
What is the wavelength of visible light?
The wavelength of visible light is a fraction of a millimetre.
77
What is the wavelength of ultraviolet waves emitted by the Sun?
The Sun emits ultraviolet waves with a wavelength of 320 nm.
78
How do you calculate the frequency of a wave?
To calculate frequency, rearrange the wave speed formula: frequency = wave speed / wavelength.
79
Why can electromagnetic waves travel through a vacuum?
Electromagnetic waves can travel through a vacuum because they do not require a medium.
80
What is the difference between waves and rays in modeling radiation?
Waves and rays are different ways of modeling what a source emits - radiation.
81
What is the significance of prefixes in electromagnetic waves?
Prefixes or powers of ten are used to express very small wavelengths and very large frequencies.
82
What should you be able to describe after studying P5.2.3?
You should be able to describe how infrared radiation, X-rays, and gamma rays are used for imaging.
83
How does a thermal imaging camera produce an image?
It produces an image called a thermogram that shows regions of different temperatures. Pixels inside a CCD absorb infrared and produce an image, with colors added by a computer.
84
What does a thermogram indicate?
It can show regions of heat due to injury or infection and problems with blood flow in blood vessels.
85
How do X-rays work for imaging?
X-rays can show if bones are broken as bones absorb many X-rays while soft tissues do not. Photographic film darkens when it absorbs X-rays.
86
Why do bones appear white on an X-ray photograph?
Bones appear white because they absorb more X-rays than soft tissues.
87
What is computerised tomography?
It is a technique that uses X-rays to create images that look like slices through the body, producing CT scans.
88
How are gamma rays used in medical imaging?
Gamma rays are used as tracers and to treat organ problems. A radioactive tracer is injected, and the patient's organs absorb it.
89
What is the role of a CCD in gamma ray imaging?
The CCD forms an image of internal organs using gamma rays emitted from a tracer.
90
How can tracers be used to find leaks?
Tracers can detect leaks in underground pipes by measuring gamma rays emitted from a leak.
91
What must doctors evaluate before using X-rays or gamma rays?
Doctors must evaluate the risks and benefits before using X-rays or gamma rays.
92
What should you be able to do after studying P5.3?
Describe how to use ray diagrams to show reflection and refraction, explain why electromagnetic waves are refracted, and describe the different ways that electromagnetic waves interact with matter.
93
How can you use ray diagrams to show reflection and refraction?
You can use ray diagrams to show what happens when electromagnetic waves hit a surface or travel through matter. To construct a ray diagram, draw lines to represent the rays, draw a normal at 90° to the surface at the point where the ray hits it, and measure the angles from the normal to the rays.
94
Why are electromagnetic waves refracted?
Electromagnetic waves, like light, are refracted when they change speed as they move from one medium to another. For example, light slows down and bends towards the normal when it goes from air into glass.
95
Where are electromagnetic waves reflected and refracted?
Electromagnetic waves are reflected from the ionosphere when sending radio waves over long distances. Lower frequency radio waves reflect, while higher frequency waves pass through.
96
What happens to electromagnetic waves depending on their wavelength?
Walls transmit radio waves and microwaves, allowing devices like televisions and mobile phones to work. Walls absorb visible light, requiring windows for visibility.
97
What is the difference between 'emit' and 'transmit'?
Emit means 'give out', while transmit means 'let through'.
98
What is the optical density?
The change in density that determines the change of speed of electromagnetic waves is the optical density.
99
What are the learning outcomes of the lesson on lenses?
After studying this lesson you should be able to:
• use ray diagrams to show the similarities and differences between convex and concave lenses
• describe what convex and concave lenses are used for.
100
What is the difference between a concave and a convex lens?
A convex lens refracts rays to a principal focus, while a concave lens spreads light out.
101
What is the focal length of a lens?
The distance from the optical centre of the lens to the principal focus.
102
How does a convex lens function as a magnifying lens?
Every time you use a lens as a magnifying lens, you are using a convex (converging) lens.
103
Can a concave lens start a fire?
You cannot set fire to anything with a concave (diverging) lens.
104
How do lenses correct vision for short-sightedness?
A concave lens spreads out light so it focuses on the retina.
105
How do lenses correct vision for long-sightedness?
A convex lens refracts light inwards so it focuses on the retina.
106
What is the purpose of ray diagrams in lens usage?
Ray diagrams predict the type, size, and position of an image based on the position of the object in relation to the lens.
107
What type of image does a magnifying glass produce?
A magnifying glass produces a virtual, magnified (bigger), upright image.
108
What type of image does a camera produce?
A camera produces a real, diminished (smaller), inverted image.
109
What type of image does a projector produce?
A projector produces a real, magnified, inverted image.
110
What is the image type produced by a concave lens?
The image produced by a concave lens is always virtual.
111
What happens to vision as one gets older?
People become more long-sighted as they get older.
112
What should you be able to explain after studying P5.3.3 Light and Colour?
You should be able to explain what filters do and how objects appear, and explain colour in terms of absorption, transmission, reflection, and scattering.
113
What is dispersion in the context of light?
Dispersion is the spreading out of white light into a spectrum due to different frequencies of light being refracted by different amounts.
114
What are the primary colours detected by the retina?
The primary colours detected by the retina are red, green, and blue.
115
How does a red filter work?
A red filter absorbs all frequencies of white light except for the small band of frequencies that we call 'red'.
116
What happens when you shine blue light on a yellow fish?
The yellow fish will look black because it absorbs all wavelengths of light except yellow.
117
What is the difference between specular and diffuse reflection?
Specular reflection gives a sharp image, while diffuse reflection does not.
118
Why does the sky appear blue?
The sky appears blue because small molecules in the atmosphere scatter light with short wavelengths, such as blue.
119
What do filters do to colours in light?
Filters subtract colours from light; they do not add colour to white light.
120
How many colours did Newton believe light was made up of?
Newton believed there were seven colours in light, so he 'invented' indigo.
