Waves Flashcards
What do waves do?
Transfer energy from one place to another through oscillations without transfer of the medium
Transverse or Longitudinal?
Transverse
Transverse or Longitudinal?
Longitudinal
Fill in the gaps
Fill in the gaps
What is amplitude and what is it measured in?
The maximum distance particles vibrate from rest position, measured in metres
What is frequency and whats it measured in?
Number of waves per second in Hertz
What is wavelength and whats it measured in?
Length of one whole wave, in metres
What’s meant by time period and whats it measured in?
Time taken for a whole wave to pass a point in seconds
In transverse waves, what’s the relationship between the oscillations and the direction of energy transfer?
Oscillations are perpendicular to the direction of energy transfer
In longitudinal waves, what’s the relationship between the oscillations and the direction of energy transfer?
Oscillations are parallel to the direction of energy transfer
Equation that links period and frequency:
period = 1/frequency
Equation for frequency
frequency = number of waves / time
Why are microwaves used for satellite communications?
They can pass through the atmosphere
What are EM Waves?
Transverse waves that transfer energy from the source of the waves
Name 2 properties of EM Waves
• Transverse
• Can travel through a vaccuum
• Transfer energy from one place to another
What is 1 micro second in standard form?
1 x 10^-6
Whats a nanosecond in standard form?
1 x 10^-9
Whats a mega second in standard form?
1 x 10^6
What’s a Giga second in standard form ?
1 x 10^9
Between Radio waves and visible light which would wave could transfer more info and why?
Visible light because shorter wavelength waves can transfer more information
What is meant by ionising radiation?
High energy waves that can cause atoms to become charged
Why is ionising radiation dangerous for humans?
It can damage living cells
What is the effect of high doses of ionising radiation on living cells?
It can kill the cell
What is the effect of lower doses of ionising radiation on living cells?
Can cause mutations or cancerous growth
What are X-Rays most commonly used for?
To form an image of your bones inside your body
Why do X-Rays only produce an image of the bone?
Because they pass through skin and soft tissue and are stopped by bone
What can high energy X-Rays and Gamma Rays be used for?
Treating cancer
Which are better emitters and absorbers of IR Radiation, Light & Shiny surfaces or Dark and Matt Surfaces?
Dark and Matt
What is meant by the angle of incidence?
The angle at which the wave hits the normal
What is the relationship between the angle of incidence and reflection?
They are equal
What is meant by refraction?
Light changes direction as it travels from
one medium to another
Why does refraction occur?
Because the speed of light is different in different materials
What do lenses do?
Change the direction of light rays by refraction
What do converging lenses do?
Make parallel rays converge to a focus
What do diverging lenses do?
Make parallel rays spread out
What is meant by principal focus?
The point where the rays appear to come from
What is meant by the focal length?
The distance from the centre of the lens to the principle focus
Are convex lenses converging or diverging?
Converging
Are concave lenses converging or diverging?
Diverging
What colours make yellow?
Red and Green
What colours make Magenta?
Red and Blue
What colours make cyan?
Green and Blue
What colour will a yellow ball appear in green light?
Green
Why does a blue ball appear black in red light?
Because there is no blue light for the ball to reflect so it’s absorbing all the light and it appears black
What type of waves are sound waves?
Longitudinal pressure waves
Which medium do sound waves travel fastest in?
Solid
What are some uses of ultrasound?
• Echolocation
• Pre-natal scanning
• SONAR
• Oceanic mapping
• Breaking Kidney stones
How is ultrasound used to treat kidney stones?
A powerful ultrasound wave causes the stone to vibrate and break into smaller parts.
What is a black body?
A perfect absorber and radiator of heat
True or False: The atmosphere is transparent to IR
False, its opaque
