Topic 6 - Waves Flashcards
(30 cards)
What happens when waves travel through a medium?
The particles oscillate and transfer energy
Particles stay in the same place
What is frequency and what is it measured in
Amount of complete waves
Hz / hertz
Describe the oscillation of transverse waves
Oscillations are perpendicular to the direction of energy transfer
What type of wave are electromagnetic waves
Transverse
Describe the oscillation of longitudinal waves
Oscillations are parallel to the direction of energy transfer
Formula for wave speed
Wave speed = frequency x wave length
When waves arrive at a boundary between 2 different materials what 3 things can happen
Reflected - bounce off
Absorbed - transfers energy to the materials energy store
Transmitted - travel through often refracted
Angle of incidence =
Angle of incidence = Angle of reflection
Angle of incidence is
The angle between the normal and incoming wave
Angle of reflection is
The angle between the normal and reflected wave
The normal line is
An imaginary line thats perpendicular to where the wave hits the boundary
Describe the 2 types of reflection
Specular reflection - Waves reflected is in the same direction and occurs on a smooth surface
Diffuse reflection - Waves reflected are scattered in different direction occurs on a rough surface
Why are diffuse reflections reflected in different directions
The normal is different for each incoming ray so the angle of incidence is different so the angle of reflection will also be different
What happens when light is reflected off of a rough surface
Surface appears matte
Don’t get a clear reflection
All EM waves travel at the same speed in
air or a vacuum
List the EM waves in increasing frequency and decreasing wavelength
radiowaves, microwaves, infrared, visible light, ultraviolet, x-ray, gamma rays
Describe refraction
When a wave passes into a different material the angle may change
If a wave crosses a boundary into a more dense material what happens
Slow down and travel towards the normal
If a wave crosses a boundary into a less dense material what happens
Speed up and travel away from the normal
Optical density is a measure of
How quickly light can travel through it
higher density travel slower
Which wave is used mainly for communication
Radio waves - long wavelengths Can diffract (bend) around the Earth and obstructions Reflected from the ionosphere (electrically charge layer in the atmosphere)
Which waves are used by satellites
Microwaves - pass easily through Earth’s atmosphere
Which wave is used in microwaves
Microwaves
absorbed by water molecules in the food
Before this they travel into the food and transfer energy -causes water to heat up
Water molecules transfer this energy to the rest of the food by heating
Which wave is used to increase/monitor temperature
Infrared
