Light !! Flashcards
learn a thing or 2 the night before the test <3 (42 cards)
What is regular reflection?
when light reflects off a very smooth surface.
What is diffuse reflection?
when light hits a rough surface, and the light scatters in many directions and doesn’t form an image.
What is the law of reflection?
The angle of incidence is equal to the angle of reflection.
Define incident ray.
the incoming ray of light.
Define reflected ray.
The ray that bounces off of the mirror.
Define the normal.
The imaginary line, perpendicular to the mirror, used to measure the angles of incidence and reflection.
What type of wavelength is light?
Visible light.
What type of wavelength is heat?
Infrared radiation.
Name the different wavelengths of the sun’s radiation.
radiowaves, microwaves, infrared, visible light, UV, X-rays, and gamma rays.
What types of images are formed by plane mirrors?
Upright, same size, same distance from mirror, laterally inverted, virtual.
Define lateral inversion.
Reversed sideways (right side is left side, vice versa).
Define a virtual image.
A visual illusion created by your brain when you look in a mirror.
How are virtual images created?
When light hits the mirror, it reflects towards your eyes creating the illusion that the light travelled in a straight line from a point inside the mirror.
What is refraction?
The bending of light.
What is reflection?
The bouncing of light off of something.
In which way does light bend when it enters a transparent substance?
Towards the normal.
In which way does light bend when it leaves the transparent substance?
Away from the normal.
What is the refractive index?
The measure of how easily light travels through a substance.
Why does light bend when going through materials of different refractive indexes?
Because the light travels slower the higher the refractive index.
How do you calculate refractive index?
Refractive index = 3 x 10^8 (speed of light in a vacuum) / speed of light in the material.
Why do depth illusions occur?
Because light from an object underwater is bent away from the normal when it leaves the water surfaces into the air. When you look at refracted light, your brain traces the light back in a straight line path.
What is a critical angle?
When light is refracted so far from the normal that when it leaves, the light runs along the boundary of the two substances.
What is total internal reflection?
when light is reflected from the boundary as though it was a mirror.
When does something perform total internal reflection?
When the angle of incidence is greater than the medium’s critical angle.
