Waves and EM Spectrum Flashcards
Name the two types of waves, and in what direction oscillations occur with respect to the direction of travel.
Transverse (oscillations perpendicular to direction of travel) and longitudinal (oscillations parallel to direction of travel).
Name the alternating areas of a longitudinal wave.
Compression and rarefaction.
What is the amplitude of a wave?
The amplitude of a wave is the maximum displacement of a point on a wave
away from its undisturbed position.
What is the wavelength of a wave?
The wavelength of a wave is the distance from a point on one wave to the
equivalent point on the adjacent wave.
What is the frequency of a wave, and how is it related to the period?
The frequency of a wave is the number of waves passing a point each second. The period is the reciprocal of the frequency.
Which motorised piece of equipment can be used to more accurately measure speed of ripples on water?
A ripple tank.
Which 3 processes can occur when a wave meets a boundary between mediums?
Absorption, reflection, and transmission.
What limits the range of human hearing, and what is this range?
The conversion of sound waves to
vibrations of solids works over a limited frequency range, limiting range of human hearing to 20Hz - 20kHz.
Name the two types of seismic waves, their types, and what mediums they can travel through.
P-waves are longitudinal and travel at different speeds through solids and liquids. S-waves are transverse and cannot travel through liquids.
What are EM waves?
Electromagnetic waves are transverse waves that transfer energy from the
source of the waves to an absorber.
List the categories of EM waves by increasing frequency.
Radio, microwave, infrared, visible
light (red to violet), ultraviolet, X-rays and gamma rays.
How do radio waves interact with oscillations in electrical circuits?
Radio waves can be produced by oscillations in electrical circuits. When they are absorbed they may create an alternating current with the
same frequency as themselves, so they can themselves induce
oscillations in an electrical circuit.
How can EM waves be dangerous to humans?
Ultraviolet waves, X-rays and gamma rays can have hazardous effects on human body tissue. Ultraviolet 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 the mutation of genes and cancer.
Suggest practical applications for each category of EM wave.
- Radio waves – television and radio
- Microwaves – satellite communications, cooking food
- Infrared – electrical heaters, cooking food, infrared cameras
- Visible light – fibre optic communications
- Ultraviolet – energy efficient lamps, sun tanning
- X-rays and gamma rays – medical imaging and treatments.
