Light Flashcards
What is light?
A form of energy
What type of waves are light waves?
Transverse waves
True or false: light travels in straight lines
True
At what speed does light travel?
300,000,000 m/s
What is a luminous object?
An object that emits light.
How do we see luminous objects?
The light from these objects enters the eyes.
What is a non-luminous object?
An object that does not emit light.
How do we see non-luminous objects?
Non-luminous objects reflect the light from luminous objects into the eyes.
Define transparent:
allows light to pass through
What is it called when an object allows some light to pass through?
Translucent
Define opaque:
Allows no light to pass through
What are the 4 rules for drawing ray diagrams?
The lines must be: straight, touch the objects, have arrows showing the direction of travel and reflected rays must join up with each other.
Define specular reflection:
when each light ray is reflected at the same angle. The AoI = AoR
Define diffuse reflection:
The reflected rays come back at different angles and in different directions.
Is a mirror an example of specular or diffuse reflection?
Specular
Is paper an example of specular or diffuse reflection?
Diffuse.
Follow this link and correctly label the ray diagram: https://qph.fs.quoracdn.net/main-qimg-d46c2b33dfc74b08ec8536db6d17cc9b
A= Incident Ray. A’= Reflected Ray. N= Normal. P= angle of incidence. Q= angle of reflection
What is the Incident Ray?
The light ray that comes from the light source and hits the object.
What is the Reflected Ray?
The light ray that bounces off of a surface and into the eyes
What is the Normal Line?
A line at 90 degrees, perpendicular to the mirror
How are periscopes made?
By positioning two mirrors at 45 degrees to each other in a tube.
What happens when light moves from a more or less dense transparent medium?
Refraction
True or false: light bends as it moves from a more or less dense medium
True
True or false: light waves do not change speed when they move from one medium to another
False
If light goes from a LESS dense medium –> MORE dense medium, will it bend towards or away from the normal?
towards
If light goes from a MORE dense medium –> LESS dense medium, will it bend towards or away from the normal?
Away
Give an example of dispersion:
white light entering a water droplet/prism is refracted into a separate spectrum of light waves
True or false: different colours refract more or less when passing through prisms and droplets.
true
Which colour is refracted the most?
Violet
Which colour is refracted the least?
Red
Objects that look white ____ all colours of the spectrum.
Reflect
Objects that look black ____ all colours of the spectrum.
Absorb
Explain why a red bottle would look red.
A red object only reflects red light and absorbs all other colours.
What happens when white light passes through a filter?
Only the colour of the filter can pass through and all other colours are absorbed.
What are the colours in a light spectrum?
Richard - Red Of - Orange York - Yellow Gave - Green Battle - Blue In - Indigo Velvet - Violet
Do pinhole cameras have a lens?
No
What do pinhole cameras have instead of a lens?
A tiny hole.
How many light rays from each point of the object enters a pinhole camera?
1
How do pinhole cameras work?
1 light ray from each point on the objects enters the camera (travelling in a straight line), and inside they cross over, so the image is seen upside down.
Label the this diagram : https://i.pinimg.com/236x/4b/39/25/4b39250884cd07e52eabdd94ce95f4cc–physics-revision-th-grade-science.jpg
1 - Cornea 2 - Pupil 3 - Iris 4 - Lens 5 - Retina 6 - Ciliary Muscle 7 - Optic Nerve
What is the function of the iris?
The coloured part of the eye and controls the amount of light which enters the eye.
What is the function of the cornea?
A transparent layer at the front of the eye and focuses much of the light entering the eye.
Are the cornea and lens convex or concave?
Convex
What is the function of the ciliary muscle?
Changes the lens shape for focusing.
What is the function of the pupil?
The hole where the light enters the eye.
What is the name of the photo-sensitive cells at the back of the eye?
Retina
What is the nerve that runs from the eye to the brain?
The optic nerve.
How is the eye similar to the pinhole camera?
The light crosses over inside so the image is formed inverted.
What is an absorber?
Anything that absorbs light.
