Waves Flashcards
What is frequency measured in?
Hertz (Hz)
What is wavelength measured in?
Metres (m)
What is the wave equation?
v = f x lambda Velocity (m/s) = Frequency (Hz) x Wavelength (m)
What is a transverse wave?
-One that looks like a snake. -The oscillations are at right angles (perpendicular) to the direction of travel -Electromagnetic Waves (No medium)
What is a longitudinal wave?
-One that has compressions and rarefactions. -The oscillations go in the same direction as the wave. -Sound
Give some examples of a transverse wave:
-Light -Microwaves -Infrared -Radio -Water waves
Give some examples of a longitudinal wave:
-Sound -Pressure (Shock) Waves
What is wavelength?
The distance between two corresponding points on a wave diagram. E.g. From crest to crest.
What is amplitude?
Amplitude is the length between the node (middle line) and the crest of a wave.
What is a crest and a trough?
Crest - The top of a wave Trough - The bottom of a wave
What do waves do?
Transfer energy, not matter. That medium always returns to its original place.
What is frequency?
The number of wave crests passing a point every second.
What is the speed equation?
Speed = Distance / Time
Waves travelling from low to high density…
Slow down and bend towards the normal
Waves travelling from high to low density…
Speed up and bend away from the normal
What happens to wavelength when waves enter a material of higher density?
It decreases
What do water waves do when going from deep to shallow water?
They slow down and bend towards the normal.
What is diffraction?
The spreading out of waves after passing through a gap.
When is diffraction most effective?
Wavelength smaller than gap - Little diffraction Wavelength bigger than gap - Lots of diffraction Large wavelength - Lots of diffraction generally
What are the parts of the eye?
What does the iris do in the eye?
Controls the amount of light which goes into the eye by expanding and detracting
What does the cornea do in the eye?
- Protects the eye (aqeous humour)
- Refracts the light to the lens
What does the lens do in the eye?
Focuses the image onto the retina
What do the ciliary muscles do in the eye
Control the power of the lens
- More powerful - relaxed (bigger curve)
- Less powerful - contracted (smaller curve)
What does the retina do in the eye?
Turns light (EM radiation) into an electrical signal
What part of the eye sends the electrical signals to the brain?
Optic nerve
What is another word for being short sighted?
Myopia
What is the technical term for having long sightedness?
Hypermetropia
What causes myopia?
- Cornea is curved too much
- Lens is too powerful
Where does myopia cause the image to be formed?
In front of the retina, far objects appear blurred
What causes hypermetropia?
- Lens or cornea is not powerful enough
Where does hypermetropia cause the image to be formed?
Behind the retina, near objects appear blurred
What is the far point of a persons vision?
The furthest distance that an unaided eye can focus a clear image
