Waves Flashcards
(43 cards)
What is a wave
A wave transfers energy without any permanent transfer of matter
What are the two types of wave
Longitudinal and transverse
What are transverse waves and give examples
Waves were the direction of oscillation is perpendicular to the direction the wave travels
e.g. Light and water
What are longitudinal waves and give examples
Waves where the direction of oscillation is the same as the wave direction
e.g. sound waves and ultrasound
What is frequency
The number of waves made per second measured in Hertz
What is wavelength
Crest to crest (one complete wavelength) measured in meters
What is time period
time for one wave to pass (seconds)
what is amplitude
Maximum height of crest or depth of trough (a)
Give the equation relating velocity frequency and wavelength
Velocity = frequency x wavelength
Give the equation relation frequency and time
Frequency = 1/time period
Time period = 1/frequency
What happens when waves go from, deep water to shallow water
Frequency doesn’t change
Velocity decreases
So wavelength decreases
(if waves hits the boundary at an angle the direction changes )
What happen to waves when they go from shallow water to deep water
Frequency doesn’t change
Velocity increase
So wavelength increases
(if waves hits the boundary at an angle the direction changes )
What happens to the waves and sound when the source is moving away from you
This is the Doppler effect
- Wavelength will increase
- Frequency will decrease
- The pitch will be lower
- Because wave speed is constant
What happens to the waves and sound when the source is moving towards you
- Wavelength will decrease
- Frequency will increase
- Higher pitch
- Because wave speed is constant
How does speed affect the doppler Effect
The faster movement the bigger the change
What is the ray going towards the plane mirror called
Incident ray
What is the ray going away from the plane mirror called
Reflected ray
What are the laws of reflection
- Angle of incidence = angle of reflection
- incident ray, reflected ray and normal all lie on the same plane
What are the properties of an image in a plane mirror
- As far being the mirror as the object is in front
- The same size as the object
- Laterally inverted
- Upright
- Virtual (It cannot be caught/projected on a screen)
When does refraction occur
Refraction occurs when light passes from one medium to another causing a change in speed and direction
- When light slows down it refracts toward the normal e.g air to glass
- When light speeds up it refracts away from the normal e.g. glass to air
What is the equation for the refractive index
n = sin i / sin r
What is the critical angle of glass
42
What is total internal reflection
When the light ray goes from a more dense medium into a less dense medium and the angle of incidence is greater then the critical angle
What is a critical angle
The angle of incidence in the denser medium that gives an angle of refraction of 90 degrees in the less dense medium
