Waves (Chapter 12 and 13) Flashcards
What are the two types of waves
Transverse and Longitudinal
What is a Transverse wave
A wave that oscillates perpendicular to the direction it is moving
What is a longitudinal wave
A wave that oscillates parallel to the direction of the wave
What is the equation for a period of a wave
Period = 1/frequency
What is a Electromagnetic wave
They are transverse waves that transfer energy from the source of the waves to an absorber
What speed do all electromagnetic waves travel at in a vacuum
The same velocity
What are the groups of electromagnetic waves
Radio waves Microwaves Infra red Visible Ultraviolet X-ray gamma ray
Which group of electromagnetic waves has the largest wavelength and lowest frequency
Radio waves
What can radio waves do in electrical circuits
When radio waves are absorbed they may create an alternating current with the same frequency as the radio wave itself, so radio waves can also induce oscillations in an electrical circuit.
what are the uses for radio waves
television and radio
what are the uses for microwaves
satellite communications, cooking food
what are the uses for infra red
electrical heaters, cooking food, infra-red cameras
Carrying signals from remote control handsets and inside optical fibres
what are the uses for visible
fibre optic communications
what are the uses for ultraviolet
energy efficient lamps, sun tanning
what are the uses for x rays
medical imaging and treatments.
what are the uses for gamma rays
medical imaging, killing cancerous cells
How can x-rays, gamma rays, ultraviolet affect the body
Ultra-violet waves can cause skin to age prematurely and increase the risk of skin cancer.
X-rays and gamma rays are ionising radiation that can cause mutation of genes and cancer.
What is radiation dose measured in
Sieverts (Sv)
What is radiation dose
It is a measure of the risk of harm resulting from an exposure of the body to the radiation
What happens when a object has a constant temperature
The amount of infrared radiation it is absorbing is the same amount it is emitting
What does the Earth’s temperature depend on
rates of absorption and emission of radiation, reflection of radiation into space.
What happens in the ear
sound waves cause the ear drum and other parts to vibrate which causes the sensation of sound. The conversion of sound waves to vibrations of solids works over a limited frequency range. This restricts the limits of human hearing.
What is the humans hearing range
20Hz to 20kHz
What are ultrasound waves
Sound waves above the frequency of 20kHz
