REFLECTION OF LIGHT WAVES

REFLECTION OF LIGHT WAVES

Definition and properties of light waves.

Light is a form of energy called Luminous energy. This energy causes a sensation of vision, enabling us to see.

Light can also be defined as the visible part of the electromagnetic waves.

Additional information about light wave (supply it)

SOURCES OF LIGHT.

Natural sources: Sun, starts, fireflies and some deep sea fish

Artificial sources: Candles. Electric touch, electric lamp, incandescent lamp, fluorescent tubes etc.

LUMINOUS AND NON LUMINOUS OBJECTS

Luminous object: This is a object either natural or artificial which produces or generate light of its own e.g. Sun, stars, electric lamps e.t.c

NON LUMINOUS OBJECT

These are the objects that you see because the sun or other light bounce off their surfaces. They reflect into your eyes e,g. tables, chairs, books etc.

Multiple Choice

The things which give off light are called

• light sources

• stores of light

• lamps

• solar energy

Multiple Choice

Mirror and diamond are considered

• light source

• not as light source

• primary source of light

• light generator

Multiple Choice

Man-made sources of light includes

• oil lamp

• burning lamp

• fire works

• all of the above

Multiple Choice

Burning Candle

• luminous

• non luminous

Multiple Choice

moon

• luminous

• non luminous

Multiple Choice

Andromeda Galaxy

• luminous

• non luminous

Multiple Choice

Earth

• luminous

• non luminous

Multiple Choice

Light is a form of

• energy

• reflection

• refraction

TRANSMISSION OF LIGHT

Opaque Object:

Translucent object:

Transparent object:

RAY AND BEAMS OF LIGHT

A light ray is the direction or path along which light energy flows. Diagramatically,rays are lines with arrows on them. They are produced in the laboratory by means of a ray box

TYPES OF RAYS

INCIDENT RAY

REFLECTED RAY

REFRACTED RAY

EMERGENT RAY

A LIGHT BEAM

It is a collection of many light rays.

• TYPES OF BEAM

• PARALLEL BEAM

• CONVERGENT BEAM

• DIVERGENT BEAM

RECTILINEAR PROPAGATION OF LIGHT

SHADOW

ECLIPSE

PINHOLE CAMERA

Multiple Choice

Light travels in a straight line

• true

• false

Fill in the Blank

A material through which light can pass.

Fill in the Blank

A material which does not transmit light.

Multiple Choice

Light travels in ........................, light ................... be bent.

• Straight line, cannot

• Straight line, can

• circular motion, can

SHADOW

A shadow is an area in which light rays from a luminous source cannot reach. The shadow of an opaque body is formed whenever the body is positioned between the source of light and a screen. A shadow takes the shape of the opaque object producing it.

FORMATION OF ECLIPSE

SOALR ECLIPSE

LUNAR ECLIPSE

ANNULAR ECLIPSE

PINHOLE CAMERA

The pinhole camera is the simplest kind of camera. It does not have a lens. It just makes use of a tiny opening (a pinhole-sized opening) to focus all light rays within the smallest possible area to obtain an image, as clearly as possible. The simple image formed using a pinhole camera is always inverted.

 Figure 12.9

MAGNIFICATION PRODUCED BY THE PINHOLE CAMERA.

Magnification is defined as the ratio of the size( or height of the image to the size ( or height of the object).

MAGNIFICATION (M) = Size of image

   Size of object.

M= height of the image

height of object

= distance of image from pinhole

distance of object from pinhole

= Length of camera

Distance of object from pinhole

EXAMPLE 1

An object 20cm high is 30cm from the hole of a pinhole camera, if the height of the image is 15m, what is the distance of the image from the pinhole.

SOLUTION

Object size = 20cm

Object height =15cm

Image height = 15cm

Distance of image from pinhole =?

Distance of object from pinhole = 30cm

Image height = distance of image from pinhole

Object height = distance of object from pinhole

 15 = V

20 30

v= 15 x 30

20

=22.5cm.

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Calculate the height of the image formed by a pinhole camera of length 12cm used to photograph an object 60cm away from the hole and 70cm high

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People cast shadow on ground as they walk because they block

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During lunar eclipse earth blocks out the

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When sun is entirely or partially blocked out by moon, it is termed as

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When sun is entirely or partially blocked out by moon, it is termed as