Grade 10 optics review

Light

Energy that travels in straight lines and in waves and does not need a medium

Visible light

Electromagnetic waves that the human eye can detect

7 distinct colours in order of lowest to highest energy

Red

Orange

Yellow

Green

Blue

Indigo

Violet

7 different types of elector magnetic waves and one example

Radio waves:TV signals

Microwaves:microwave ovens astronomy

Infrared light: lasers or remote controls

Visible light: rainbows, concert lighting

Ultraviolet light:black lights tan

X-rays; cancer treatment

Gamma rays; cancer treatment

Incandescence

Light produced by heat

Luminescence

Produces it's own light

Phosphorescence

Absorbs Uv light and releases over long period of time

Fluorescence

Immediate emission of visible light as a result of absorption of Uv light(glow stick)

Chemi luminescence

Production if light as a result of a chemical reaction

Bioluminescence

Living creature had chemical reaction with little to no heat produced

Triboluminescence

Light from friction

Transparent

All light rays travel through, you can see clearly through it ex. Window

Translucent

Only some light rays travel through, images are less clear ex. Jello

Opaque

No light can get through ex. Wall

Light emitting diode (LED)

Light produced from electric current flowing through semiconductors

Laser

Consists of electromagnetic waves of exactly the same energy level traveling in unison In the same direction. Focused and pure color

Laws of reflection

1. The angle of incidence equals the angle of reflection

2. The incident ray, the reflected ray and the normal all lie on the same plane

Specular reflection

Reflection of light off a smooth surface

Diffuse reflection

Reflection of light off a dull or irregular surface

Characteristics to describe images

SALT:size, attitude, location and type

Virtual image

Light is not coming from an actual image location : behind mirror and in front of lenses

Real image

Would be seen on a screen, Infront of a mirror and behind a lens

Concave mirror

Aka converging, bulges out like it's part of a sphere

Convex mirror

Aka diverging, bulges in

Principal axis

Line through centre of mirror and centre or curvature

Vertex

Point where principal axis meets mirror

Refraction

Bending or changing direction of light when it travels from one medium to another

Index of refraction

The ratio of the speed of light in a vaccuum to the speed of light in a medium , n=c/v; this value is also equal to the ratio of the sine of the angle of incidence in a vacuum to the sine of the rafracted ray in a medium n=sin

Light bends towards the normal when

The speed of light In the 2nd medium os less than the speed of light In the 1st medium

Light bends away from the normal when

The speed of light in the 2nd medium is more than the speed of light on the 1st medium

Critical angle

Angle if incidence that results in an angle of refraction of 90 degrees

Total intern reflection

The situation when the angle of incedence is greater than the critical angle

To have total internal reflection,

Light must be travelling more slowly in the 1st meduim than the second

Fibre optics

Technology that uses light to transmit information along a glass cable

Apparent depth

The depth that an object appears to be at due to the refraction of light In a transparent medium

Mirage

A virtual image hat forms as a result of refraction and total internal reflection in earths atmosphere

Dispersion / rainbow

The desperation of white light into it's constituent colours

Converging lens

Thickest in the middle and causes incident parallel light rays to converge through a single Pinot after refraction

Diverging lens

Thinnest in the middle and causes incident parallel light rays to spread apart after refraction

Optical centre

Point at the exact centre of the lens

Principal focus

The point on the principal axis of a lens where light rays parallel to the principal axis converge after refraction

Emergent ray

Light ray that leaves a lens after refraction

Thin lens equation

1/do+1/di=1/f

Magnification equation

M=hi/ho

M=-di/do

Accommodation

Changing shape of the eye lens by eye muscles to allow a sharply focuses image to form on the retina

Hyperopia

The inability of the eye to focus light from near objects

Presbyopia

Form of far sighted ness from age

Myopia

Inability of the eye to focus on distant objects