Sound and Light Flashcards
What are sound waves?
Waves are transfers of energy, not matter. They involve vibrations (oscillations).
What is amplitude?
Amplitude is the volume. On a diagram, the amplitude is the distance from the middle to the peak/trough.
What does the amplitude depend on?
Energy in the vibrations.
What does low/high amplitude sound have?
- Low amplitude sound has a smaller range of movement (less energy).
- High amplitude sound has a larger range of movement (more energy).
What does the A represent?
It is the Greek letter lambda that represents wavelength.
On a diagram, what is the top part of the wave called?
The peak/crest.
On a diagram, what is the bottom part of the wave called?
The trough.
What is frequency (Hz)?
The number of waves that pass a fixed point in a second measured in Hertz. 1 Hz = 1 sound wave per second.
What is the wavelength?
The distance from one point on a wave to the same point on the next wave.
What is the pitch?
Pitch relates to the sound that we hear rather than the volume. High pitch sounds have a higher tone eg: a mouse’s squeak. Low pitch sounds have a lower tone eg: a bear’s growl.
How is pitch shown on an oscilloscope trace?
It is shown by how many waves there are (frequency).
How does sound travel through the ear?
1) Sound waves are collected by the ear lobe/pinna.
2) The sound waves travel along the ear canal.
3) The waves make the eardrum vibrate.
4) The small ear bones (ossicles) amplify the vibrations.
5) The cochlea turns these into electrical signals.
6) The auditory nerve takes the signals to the brain.
What is the pinna?
It is made of cartilage covered by skin. It funnels sound into the ear canal.
What are the ear bones/ossicles?
3 tiny bones that amplify and transmit the vibrations from the eardrum to the cochlea.
What is the cochlea?
An organ at the back of the ear filled with fluid. Receptor cells change vibrations in the fluid into electrical impulses.
What is the eardrum?
A thin, tough layer of tissue at the end of the auditory canal. Sound waves make the eardrum vibrate.
What is the ear canal?
A short tube that transmits sound from the pinna to the eardrum.
What is light?
Light is a form of energy we use to see things. Objects that create light are sources of light or luminous sources.
Why do we see non-luminous objects?
A source of light, like a lightbulb, emits light. This light reflects off an object and into your eye. You see the object when the light is absorbed into your eye.
Why can’t you see clearly through translucent objects?
The light can travel through them, but gets scattered, making it harder for you to see through it clearly.
When drawing ray diagrams, what is the focal length?
The distance from the center of the lens to the imagining point (where the light starts).
What does the speed of light depend on?
The speed of light depends on the medium through which the light is travelling.
What happens when light enters a denser material?
When light enters a denser material (eg: from air into glass), the speed of light decreases. This causes the light to bend or refract.
How is the speed of light affected by density?
The speed of light is affected by the density of the material through which it is travelling.
What happens when light enters a more dense medium?
When light enters a more dense medium (eg: from air into water), it’s speed decreases and this is why fraction occurs.
How do you draw a ray diagram?
1) Shine your light in so that it hits where the normal line meets the glass.
2) Draw a line showing where the ray comes out the other side of the glass.
3) Take the glass block away and connect the 2 lines.
4) Measure the angle of incidence from the normal to your line using a protractor.
5) Measure the angle of refraction from the normal to your line.
What are the 3 primary colours of light?
Red, green and blue.
What are the 3 secondary colours of light?
Yellow, cyan and magenta.
What happens when coloured light hits a surface of the same colour?
It is reflected.
When white light passes through a coloured filter, what are the only wavelengths that can pass through?
The only wavelengths of light that can pass through a coloured filter are ones that are the same colour as the filter.
What colour does an object appear when all the wavelengths of light are absorbed.
The object appears black.
What are convex lenses?
Our eyes are equipped with convex lenses to help us focus the light and enable us to see. The point where the rays cross is called the focus or focal point.
What is the cornea?
A clear, tough coating on the front of the eye (like a window).
What is the iris?
Coloured part of the eye, which is a circular muscle. The iris controls the size of the pupil.
What is the pupil?
Allows light into the eye. Gets big in dim light, small in bright light.
What is the lens?
Flexible structure that changes shape to focus light on to the retina.
What is the blind spot?
Point where the nerves are missing the fibres from the retina enter the optic nerve here.
What is the retina?
Contains millions of nerve cells which set up electrical signals when light strikes them. The nerve cells are called rods and cones.
What is the optic nerve?
Carries signals from the retina to the brain.
What are decibels?
The unit used to measure the loudness of the sound.
On sound waves, how can you tell what is the pitch and what is the volume?
- The pitch is the amount of waves there are.
- The volume is the height of the waves.
