Light and Sound Flashcards
What does a wave transfer?
Energy, not matter.
In a transverse wave, how do the particles vibrate?
The vibration of the particles is perpendicular to the direction of energy.
In a longitudinal wave, how do the particles vibrate?
The vibration of the particles is parallel to the direction of energy.
What is a transverse wave?
A wave where the vibration of the particles is perpendicular to the direction of oscillation.
What is a longitudinal wave?
A wave where the vibration of the particles is parallel to the direction of oscillation.
In a longitudinal wave, what are areas where the particles are pushed together called?
Compressions.
In a longitudinal wave, what are areas where the particles are spread apart called?
Rarefactions.
What does a louder sound have?
A higher amplitude.
What does a high-pitched sound have?
A higher frequency.
Give an example of a longitudinal wave.
Sound.
Give an example of a transverse wave.
Light (also radio, microwaves, infra-red, UV, X-ray, gamma ray, water).
What is an object that gives off light known as?
Luminous.
How can we see non-luminous objects?
Because light is reflected off the object.
When light hits an object and ‘stops’, what is it known as?
Absorption.
When light hits an object and bounces off, what is it known as?
Reflection.
What is a material that lets light through without scattering known as?
Transparent.
What is an opaque material?
A material that does not let light pass through.
What is an object that scatters light as it passes through known as?
Translucent.
How do the angle of incidence and the angle of reflection compare?
They are equal/the same.
What is the first step in drawing a reflected ray?
Extend the incident line to the surface.
What is refraction?
The change in direction of a wave when it changes speed.
When does refraction occur?
When a wave moves into a different substance.
What happens if the speed of a wave decreases as it moves into a new substance?
It will bend towards the normal line.
What happens if the speed of a wave increases as it moves into a new substance?
It will bend away from the normal line.
What occurs when the angle of incidence is greater than the critical angle?
All the light will be reflected/total internal reflection.
What is total internal reflection?
When all the light is reflected with a material (e.g. a piece of glass).
Give two examples of where total internal reflection is found in real-life applications.
Periscopes (submarines), internal cameras (medicine), fibre-optic.
What is the name of the coloured circle around the pupil?
Iris
What is the purpose of the lens in the eye?
To focus light onto the retina
What do you call the black part of the eye?
Pupil
It is the opening that lets light in.
What is the retina?
Light-sensitive layer at the back of the eye, made up of rods and cones.
What is the purpose of the optic nerve?
Carries messages from the retina to the brain.
Why do we end up with an inverted image formed on our retina when we look at an object?
Because light is refracted by the cornea and lens in our eye.
What three colours of light can our eyes detect?
Red, green, blue
What are the colours of the spectrum that make up white light?
Red, Orange, Yellow, Green, Blue, Indigo, Violet
Use ROY G. BIV.
The colour of a light depends on what feature of a wave?
Frequency
When light enters a prism it splits into the colours of the spectrum, what do we call this effect?
Dispersion
Why does a blue object appear blue when a white light is shone upon it?
It reflects blue light. It absorbs all other colours of light.
Why do black objects appear black?
They absorb all colours that are shone on them. No light is reflected.
When red and green light is combined, what colour is formed?
Yellow
When red and blue light is combined, what colour is formed?
Magenta
When blue and green light is combined, what colour is formed?
Cyan
Sketch a low-pitched sound becoming a high-pitched sound (the volume remains constant).
Sketch required
Sketch a quiet sound becoming a loud sound (the pitch remains unchanged).
Sketch required
If a sound is becoming lower pitched, what is decreasing?
The frequency
If a sound is becoming lower in volume, what is decreasing?
The amplitude
What formula can we use to calculate the speed of sound?
speed = distance/time
Do sound waves travel fastest in solid, liquid or gas?
Solid
Do light waves travel fastest through a solid, liquid or gas?
Gas (light travels fastest through a vacuum)
When calculating the speed of sound using an echo, what must you remember?
The echo travels to an object and back again (you may need to double the distance).
