Optics

What are the two conditions needed to see light?

1. A light source is needed
2. An obstruction (something for the light to bounce off of) is needed

Ray diagram

diagram that shows the path of light from one location to another with a light ray drawn in a straight line

What happens to "white light" when it passes through a prism?

Refraction → split into many colors
- colors have different wavelengths that bounce off of prism at slightly different angles
- will appear separated

Is it possible for an object viewed in red light to appear white?

No, there is no white light for the object to reflect in red light.

Using a flat mirror provides an ____________ reflection of the object.

exact

C (center of curvature)

C = 2f
center of sphere formed by lens/mirror

When an object is located between the focal point and concave mirror, the resulting image is...

virtual
upright
enlarged

When an object is located between the focal point and center of a concave mirror, the resulting image is...

real
inverted
enlarged

When an object is located beyond the center of a concave mirror, the resulting image is

real
inverted
reduced

When an object is placed at the center of curvature of a concave mirror, the resulting image is...

real
inverted
same size as object

Why are concave mirrors used as makeup mirrors?

- allow for magnification
- provide enlarged, upright images
- have large focal point, which will result in more magnified image
- move farther away → image will appear inverted

An image formed by a convex mirror is...

virtual
upright
reduced

An image formed by a plane mirror is...

virtual

Real images formed by concave mirrors are always...

inverted

Convenience stores have convex mirrors because...

- provide virtual, upright, reduced images
- allows wider view of store
- no need for expensive security camera system

Why might light rays change direction when moving from one type of material to another?

- material density
- index of refraction

index of refraction

C = nv, C = speed of light in vacuum = 3 * 10^8 m/s
measure of the bending of a ray of light when passing from a vacuum to a medium

Snell's law

sinθ1/sinθ2 = n2/n1

What happens when you submerge a glass in vegetable oil?

- have same index of refractions (~1.5)
- glass will appear to disappear when submerged in oil

Light bends away from the normal line when...

light is moving from a material with a higher index of refraction to a material with a lower index of refraction

Critical angle

- greatest angle light can strike when traveling from one medium to another without being totally reflected in first medium
- going beyond critical = total internal reflection
- used in fiber optic glass and light pipes: light will internally reflect, will transmit digital signals without losses out the side of the wall of the fiber

Convex lens cause light rays to...

converge

concave lens cause light rays to...

diverge

Why do cameras and telescopes have two convex lens?

need second lens to make image upright

When an object is placed between the focal point and convex lens, the resulting image is...

virtual
upright
enlarged

When an object is placed between the focal point and center of a convex lens, the resulting image is...

real
inverted
enlarged

When an object is placed beyond the center of a convex lens, the resulting image is...

real
inverted
reduced

When an object is placed between the focal point and center of a concave lens, the resulting image is...

virtual
upright
reduced

Luminous source

source that produces light rays

Illuminated source

source that is lit by light rays
- becomes visible as a result of the light reflecting off it
- ask: "is light being reflected off of it and providing a light source?"

Extended source

a luminous source that emits light in all direction from each point on its surface
- if light illuminated from points perpendicular to surface, then some spots would be completely dark because light would not be able to reach those parts

Flat mirror

mirror with flat surface

normal line

perpendicular to mirror surface

reflected ray

ray reflected off mirror

incident ray

ray that strikes mirror

angle of incidence

the angle between the incident ray and the normal

angle of reflection

The angle between the reflected ray and the normal

law of reflection

the angle of incidence is equal to the angle of reflection

Image location

where the image is located relative to mirror

Object distance

distance from object to mirror

Image distance

distance from image to mirror

Virtual image

at any position where the paths of reflected rays seem to originate behind mirror

focal length (f)

distance from focal point to mirror/lens

focal point

location where parallel incident rays converge

real image

image that appears to come from a point where rays actually meet

virtual image

image that appears to come from a point where rays do not actually meet (need to extend rays)

mirror equation/thin lens equation

1/f = 1/do + 1/di

magnification equation

m = hi/ho = -di/do