Grade 10 : Light and Geometric Optics

Index of Refraction

The ratio of the speed of light in a vacuum to the speed of light in a medium.

Properties of Light

- Travels at extremely high speeds

- Travels in straight lines

Medium

Any substance that through which energy can be transferred.

Radiation

A method of energy transfer that does not require a medium;the energy travels at the speed of light.

Electromagnetic Wave

A wave that has both electric and magnetic parts, does not require a medium, and travels at the speed of light

Visible light

Electromagnetic waves that human eye can detect.

Electromagnetic Spectrum

The classification of electromagnetic waves by energy.

Luminous

Produces its own light.

Non Luminous

Does not produce its own light.

Incandescence

The production of light at a high temperature.

ex. Incandescence light bulbs

Electric Discharge

The process of producing light by passing electric current though gas.

ex. Neon sign

Phosphorescence

The process of producing light by the absorption of ultraviolet light resulting in the emission of viable light an extended period of time.

ex. Glow in the dark toys

Fluorescence

the immediate emission of visible light as a result of the absorption of ultraviolet light.

ex. Fluorescent light bulbs

Cheiluminescence

The direct production of light as the result of a chemical reaction with little or no heat produced.

ex. glow sticks ( break for chemicals to react )

Bioluminescence

the production of of chemiluminescsence when occurs in an organism.

ex. Fireflies

Triboluminescence

the production of light from friction as a result of scratching, crushing, or rubbing certain crystals.

ex. Lifesavers

LED

Light produced as a result of an electric current flowing in a semi conductors.

Light Ray

A line on a diagram representing the direction and path that light is travelling.

Incident Ray

Light emitted from a source that strikes an object.

Transparent

Objects can clearly be seen thought.

Translucent

Light goes thought, objects can not be seen clearly.

Opaque

Light can not be seen at all.

Reflection

The bouncing back of light from a surface.

Reflected ray

The light ray that bounces off a surface.

The Normal

A line perpendicular to a mirror surface.

Angle of Incidence

The angle between the incident ray and the normal.

Angle of Reflection

The angle between the reflected ray and the normal.

Types of Mirrors

Plane mirror - flat

Curved mirror - concave

- convex

Using S.A.L.T

S -----> Size ( smaller, larger, same )

A -----> Attitude ( upright, inverted )

L ------> Location ( in-front, behind )

T ------> Type ( virtual, real )

Law Of Reflection

Angle of incidence = Angle of reflection

Centre of Curvature

The center of the sphere whose surface has been used to make the mirror.

Principal Axis

The line through the centre of curvature to the midpoint of the mirror.

Vertex

The point where the principal axis meets the mirror.

Focal Point

The point at which rays parallel to the principal axis reflect and meet.

Concave

A mirror shaped like a part of the surface of a sphere in which the inner surface is reflective.

Convex

A mirror shaped like a part of the surface of a sphere in which the outer surface is reflective.

Refraction

The bending or change in direction of light when it travels from one medium to another.

Speed of Light

3.0 x 10^8 m/s

Angle of Refraction

The angle between the refracted ray and the normal.

Rules of Refraction

-When light enters a more refractive medium it will bend toward the normal

-If it enters a less refractive medium, it will bend away from the normal

Index of Refraction Formula

N= C/V

N= Index of Refraction

C= Speed of Light

V= Speed of Light in Medium

Apparent Depth ( Refracted Phenomena )

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

Mirage

a virtual image that forms as a result of refraction and total internal reflection in earth's atmosphere.

Convering Lens

A lens that is thickest in the middle and and that causes incident parallel light rays to converge through a single point after refraction.

Diverging Lens

A lens that is thinnest in the middle and that causes incident parallel light rays to spread apart after refraction.

Optical Centre

Point at the centre of the lens.

Thin Lens Equation

Th e mathematical relationship among F, di, do

Thin Lens Equation Formula

1/f = 1/di + 1/do

F= Focal length

di= Distance to Image

do= Distance to Object

Iris

A ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening.

Lens

The transparent structure behind the pupil that changes shape to help focus images on the retina.

Pupil

The adjustable opening in the center of the eye through which light enters.

Cornea

The clear tissue that covers the front of the eye.

Retina

Light sensitive layer of the eye; contains rods and cones.

Optic nerve

The nerve that carries neural impulses from the eye to the brain.

Rod Cells

Cells in the retina that detect shapes and movement. ( also works in low light )

Cone Cells

Cells in the retina that detect colors. ( red green, blue )

Far-sightedness (hyperopia)

The inability of the eye to focus light from near objects.

Near-sightedness (myopia)

The inability of the eye to focus light from distant objects.

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