Flashcards in Unit 2 - Topic 1 - Waves, Sound and Light Deck (55):
What do waves transfer?
Waves transfer energy and information from one point to another through vibrations/oscillations.
Give some examples of longitudinal waves.
Primary earthquake waves
Give some examples of transverse waves.
Secondary earthquake waves
Wavelength, represented by the Greek letter (lambda), is the distance between successive crests.
Frequency - f is the number of compete waves generated per second.
Speed - V of the wave is the distance moved by a crest or any point on he wave in 1 second.
Amplitude - a is the height of a crest/peak or the depth of a trough measured from the undisturbed position of what is carrying the wave.
What is the quantitative relationship between wave speed, wavelength and frequency?
V = Speed
f = Frequency
W = Wavelength (lambda)
Form two equations equal to f, frequency.
V=fW ---> f=V/W
f = 1/T
T = Time period, time between successive crests or troughs.
When a wave travels from a less-dense to a more-dense medium, it's speed ...
When a wave travels from a more-dense to a less-dense medium, it's speed ...
Write down the echo principle formula.
S = 2nd/t
S = Speed of the waves
n = Number of claps
d = Distance to reflective surface
2d = Distance to reflective surface and back (round trip)
t = Time taken
What are the different types of radiation in the electromagnetic spectrum?
What is the typical wavelength of gamma rays?
What is the typical wavelength of X-rays?
What is the typical wavelength of ultra-violet radiation?
0.1 micrometers - 0.4 micrometers
What is the typical wavelength of visible light?
0.4 micrometers - 0.7 micrometers
What is the typical wavelength of infrared radiation?
What is the typical wavelength of microwave radiation?
1cm - 1m
What is the typical wavelength of radio wave radiation?
1m - 1km
At what speed do all electromagnetic waves travel in a vacuum?
What produces sound?
Sound waves with frequencies above 20KHz are called ...
What are some applications of echoes?
1. Ships use ultrasonic waves to measure the depth of the sea and to detect shoals of fish.
2. In industry ultrasonic waves are used to reveal flaws in welded joints.
3. Reverberation is desirable in a concert hall to stop it sounding 'dead', but too much causes 'confusion'. Modern concert halls are designed for the optimum amount of reverberation. Seats and some wall surfaces are covered with sound-absorbing material.
What are some contemporary applications of ultrasound in industry and medicine?
Ultrasound has many applications in medicine. These include:
1. Checking the condition of a foetus.
2. Investigating liver problems.
3. Investigating heart problems.
4. Breaking down kidney stones and stones elsewhere in the body.
5. Measuring the speed of blood flow in the body.
What are the uses of radio waves?
What are the uses of microwaves?
What are the uses of infrared radiation?
Short range communications
Television remote controls
What are the uses of visible light?
What are the uses of ultra-violet radiation?
Detecting forged banknotes
What are the uses of X-rays?
Observing the internal structure of objects.
Airport security scanners.
What are the uses of gamma rays?
Sterilising food and medical equipment.
Detection of cancer and its treatment.
Over-exposure to certain types of electromagnetic radiation can be harmful. The higher the frequency of the radiation, ...
The more damage it is likely to cause the body.
What are the dangers of microwave radiation?
Microwaves cause internal heating of body tissues.
What are the dangers of infrared radiation?
Infrared radiation is felt as heat and causes skin burns.
What are the dangers of X-rays?
X-rays damage cells, causing mutations (which may lead to cancer) and cell death.
What are the dangers of gamma rays?
Gamma rays also damage cells, causing mutations (which may lead to cancer) and cell death.
Images formed in a plane mirror are ...
What is a real image?
A real image is one which can be produced on a screen and is formed by rays which actually pass through it.
What is a virtual image?
A virtual image cannot be formed on a screen and is produced by rays which seem to come from it but do not pass through it.
The image in a plane mirror is ...
What is refraction?
Refraction is the bending of light as it passes from one media to another.
What is a medium?
A medium is a particular material with uniform density.
Why can a spectrum be produced on a screen?
A spectrum can be produced on a screen because different colours of light travel at different speeds in glass.
The greater the change in density of the medium, the greater the amount of refraction, the greater the change in (blank)
What is a spectrum?
A band of colours obtained after shining a bright white light through a triangular glass prism.
What is the name of the angle of incidence within the glass block which produces an emerging ray with an angle of refraction of 90°?
The critical angle
What happens when the critical angle is exceeded?
Total internal reflection
What is an optical fibre?
Several thousand single, very thin glass fibres taped together to form a flexible light pipe.
What role does total internal reflection play in optical fibres?
A ray of light entering the fibre undergoes total internal reflection at a bend. This means that the light cannot escape and so it travels along the fibre by a series of internal reflections.
The point onto which light rays parallel to the principle axis converge.
A point on the axis of a lens located so that any ray of light travelling parallel to the principle axis which intersects is point suffers no deviation. This also applies to rays at any angle.
The distance between the optical centre of a lens and its principle focus.
A line which passes through the centre of the surface of a lens.