Physics - Waves Flashcards
What is a transverse wave?
The vibrations of the waves are perpendicular to the direction of energy transfer
What is a longitudinal wave?
The vibrations of the waves are parallel to the direction of energy transfer
Define amplitude
the maximum displacement of a point on a wave away from its undisturbed position
Define wavelength
the distance from a point on one wave to the equivalent point on the adjacent wave
What is equation linking time period and frequency?
Time period = 1 ÷ frequency
What are the units for frequency?
Hz or Hertz
What is equation linking wave speed, frequency and wavelength?
wave speed = frequency × wavelength
Are electromagnetic waves transverse or longitudinal?
Transverse
What do EM waves transfer?
Energy
Explain why EM waves are not mechanical waves.
They can travel through a vacuum
What is order of the electromagnetic waves from highest frequency to lowest frequency?
Gamma, X-Rays, Ultraviolet, Visible light, Infra-red, Microwave, Radio waves
What can occur when a EM wave meets a substance?
absorbed, transmitted, refracted or reflected
Why does refraction happen?
a change in velocity
How can EM waves be produced?
Changes inside an atom
How can radio waves be produced?
Oscillations in an electrical circuit
How can we detect radio waves?
they create an alternating current with the same frequency
What is Radiation dose
a measure of the risk of harm resulting from an exposure of the body to the radiation.
Which EM waves are ionising?
X-rays and Gamma
What are the dangers of ultraviolet waves?
can cause skin to age prematurely and increase the risk of skin cancer
What are the dangers of X-rays and Gamma rays?
can cause the mutation of genes and cancer
What can radio-waves be used for?
television and radio
What can microwaves be used for?
satellite communications, cooking food
What can infrared be used for?
electrical heaters, cooking food, infrared cameras
What can visible light be used for?
fibre optic communications
What can ultraviolet be used for?
energy efficient lamps, sun tanning
What can gamma rays be used for?
Sterilising equipment, medical treatment
What can x-rays be used for?
medical imaging and treatments
Why are X-rays used for medical imaging?
they pass through flesh but not bone
Why are gamma rays used for treating cancer and sterilising medical equipment?
high doses kills cells and bacteria
Which surfaces absorb radiation?
all surfaces, black is the best absorber
Which surfaces emit radiation?
all surfaces, black is the best emitter
