curved mirrors & lenses

2 types of curved mirrors

Concave & Convex

Concave

Converging mirrors

To meet in a common place

Convex

Diverging mirrors

To spread apart

Center of curvature

Center of the larger sphere (circle) of the mirror

Principal axis

Line thru the center of curvature to the midpoint of the mirror

Focus

Point where light parallel to the principal axis meets

Vertex

Point where the principal axis meets the mirror

Concave rules

1. Parallel ray bounces thru the focus

2. Thru the focus bounces parallel

3. Thru the center reflects back to the way it came

4. Thru the vertex reflects like a flat mirror

Convex rules

1. ray parallel to the principal axis is as if it had come through the focus

2. ray aimed to the centre of curvature on the other side is reflected

3. ray aimed to the focus is reflected parallel to principal axis

The law of reflection states that…

When an object hits a surface, its angle of incidence will equal the angle of reflection. Only true when the object is light and the surface is a flat smooth mirror

Transparent

All light goes thru

Translucent

Some light goes thru

Opaque

No light goes thru

Normal line

Imaginary line perpendicular to the surface

Angle of incidence

Angle in which the light enters

angle in between the normal and the incident ray

Angle of reflection

Angle in which the reflected ray bounces off the surface

Angle in between the normal and the reflected ray

Virtual image

Image formed by light coming to an apparent

Upright

Real image

Reproduction of an object, produced by an optical device

Inverted

Lateral Inversion

Placement of image in a plane mirror that is backwards and in reverse order

SALT

S - Size of an image (size, smaller, larger)

A - Attitude of an image (upright/inverted)

L - Location of image

T - Type of image (real/virtual)

2 types of lenses

converging and diverging

converging lens rules

1. ray parallel to the principal axis passes thru focal point on the other side

2. ray passes thru center of lens doesn’t get reflected

3. ray passes thru focal point in front of lens emerges parallel to the principal axis on the other side

can make both real and virtual images

diverging lens rules

1. ray parallel to the principal axis deflects and appears to come from the focal point in front of lens

2. ray passes thru center of lens doesnt deflect

3. ray would pass thru focal point on the other side of lens but instead emerges parallel to the principal axis

always produces same image characteristics.

S - small

A - upright

L - same side of lens as object

T - virtual

refraction

bending/change in direction of light when it travels to one medium to another

angle of refraction

angle between the refracted ray and the normal

rules of refraction

1. incident ray, refracted ray, normal are all in the same plane. incident and refracted ray are on the opposite sides of the line that separates the two media

2. light bends towards the normal when speed of light in 2nd medium is slower than the speed of light in the first medium

3. light bends away from the normal when speed of light in the 2nd medium is faster

slower towards, faster away

lens equation

1/f = 1/do + 1/di

magnification equation

how big image is compared to the object

m = hi/ho = -di/do

conventions of lens equation

do = ALWAYS positive

di = positive is real img, negative is virtual img

ho & hi positive = upright, negative = inverted

f = positive for converging, negative for diverging

magnification equation = if negative, image is inverted

what are the 2 conditions needed for total internal reflection

1. light must travel to more dense medium to less dense medium

2. angle of incidence is large enough that refraction does not occur in the 2nd medium (angle of incidence is greater than the critical angle)

critical angle

the angle of incidence that produces a 90° refracted ray

symbol: θc

θc = θi

with a _____ critical angle, you will get more internal reflection

with a small critical angle, you will get more internal reflection

with a ___ critical angle, you will get less internal reflection

with a big critical angle, you will get less internal reflection

when angle of incidence is ____ ____ the critical angle, light ray is reflected like a mirror

when angle of incidence is greater than the critical angle, light ray is reflected like a mirror