Waves Flashcards
What do waves transfer?
energy and information
What is frequency?
the number of waves passing through a point per second (Hz)
Define wavelength
the distance between two adjacent peaks on a wave
Define amplitude
The maximum displacement of the wave from its equilibrium position
What is the period of the wave?
the length of time it takes for one full wave to pass through a point
How do you calculate the wave speed?
wavelength * frequency
State an equation linking frequency and period of a wave
Frequency = 1 / Time Period
What is a longitudinal wave?
Vibrations are parallel to the direction of energy transfer
What is a transverse wave?
a wave with oscillations that are perpendicular (90 degrees) to the direction of energy transfer
Explain the “doppler effect”
When a wave source is moving towards the observer: the observed frequency increasing and the observed wavelength decreases
When a wave source is moving away from the observer: observed frequency decreases and observed wavelength decreases (WAVE SPEED = WAVELENGTH * FREQUENCY)
What type of waves are electromagnetic waves?
transverse
What are the 7 electromagnetic waves?
radio, microwaves, infra-red, visable light, ultraviolet, xrays, gamma rays
What are the uses of radio waves?
communications, satellite transmissions
What are microwaves used for?
cooking in microwave ovens, satellies, communications
What are infrared used for?
cooking, thermal imaging, telivision remote controls
What are uses of visable light?
SIGHT, photography, optical fibres
What is the use of ultraviolet rays?
security marking and flourescent lamps
What are some uses of xrays?
scanners, medical imaging
What are the uses of gamma rays?
Used to sterilise food, medical equiptment, cancer diagnosis
What are the risks of gamma rays?
can cause mutations or damage to body cells
What are the disadvantages of microwaves?
can cause heating of internal tissues in the body
What is the disadvantage of infrared radiation?
it can cause skin burns
What is the disadvantage of ultraviolet?
it can cause skin cancer or eye conditions
What is the normal?
a line perpendicular to the boundary
What happens when light is reflected?
it is reflected off a flat surface - the angle of incidence is the same as the angle of reflection
What happens when light is refracted?
the light changes speed and direction
- if it is more dense, the light will travel slower and bend towards the normal
- if it is less dense, the light will travel faster and bend away from the normal
