Light and our Eyes Flashcards
What are luminous objects?
Objects that produce light.
What form is light?
A wave.
Give an example of a luminous object.
The Sun
What are non-luminous objects?
Objects that don’t produce light.
Give an example of a non-luminous object.
A book
What do light waves transfer?
Energy
What does light travel fastest through and why?
Light travels fastest through a vacuum because there are no particle obstructing it.
What is reflection?
Reflection of light is when a light ray bounces off a surface and changes direction, continuing to travel in a straight line but in a different direction.
What is the difference between specular reflection and diffuse reflection?
Specular reflection is when light rays reflect off a smooth, shiny surface, so there is a clear reflection. Diffuse reflection is when light rays are reflected off a rough surface, and the light rays are scattered.
Angle of ______ = angle of _______
incidence and reflection
What is the normal?
A line at a right angle to the surface.
How are the angles of incidence and reflection measured?
Between the incident light ray / reflected light ray and the normal.
What is refraction?
Refraction happens when light rays move through a more or less dense substance.
Will light travel through transparent and opaque materials?
Yes to transparent but not to opaque.
What does opaque mean?
Not see-through.
What is a medium?
Any substance that light travels through.
What happens when light goes from a more dense medium to a less dense medium?
The light bends away from the normal.
What happens when light goes from a less dense medium to a more dense medium?
The light bends towards the normal.
How do we see?
When a luminous object produces light, it reflects off other non-luminous objects, and some of that reflected light goes into our eyes.
What does a lens do?
A lens refracts light.
What is the different between convex and concave lenses?
Convex lenses bulge outwards, and cause rays of light to converge to a focus, whereas concave lenses scatter light rays.
What is the cornea?
A transparent window with a convex shape in our eyes.
Why does the convex lens behind the cornea change shape?
To focus light from objects at varying distances.
What is the iris?
The coloured part of our eye, controls the amount of light entering the eye.
What does the retina do?
Forms images. Retina cells are photosensitive (sensitive to light).
What is an absorber?
Something that absorbs the energy carried by light waves.
