Summary of light shadows and reflection

Summary

Light:Light, electromagnetic radiation that can be detected by the human eye.

Shadows:A shadow is a dark (real image) area where light from a light source is blocked by an opaque object.

Reflection:The production of an image by or as if by a mirror

Luminous

Objects like the sun that give out or emit light of their own are called luminous objects.

TRANSPARENT, OPAQUE AND  TRANSLUCENT OBJECTS OBJECTS

TRANSPARENT:: If you are able to see clearly through an object, it is allowing light to pass through it and is transparent. ex air, water, and clear glass 

Opaque object:

If we cannot see through an object at all, it is an opaque object

Ex: wood, stone

Translucent:There are some objects through which we can see, but not very clearly. Such objects are known As translucent. Ex rosted glass and some plastics

WHAT EXACTLY ARE SHADOWS

A  shadow is a dark real image area where light  from a light source is blocked by an opaque object.

A PINHOLE CAMERA

A pinhole camera is a simple camera without a lens but with a tiny aperture effectively a light-proof box with a small hole in one side. Holding the pinhole camera look through the open face of the smaller box. You should use a piece of black cloth to cover your head and the pinhole camera.

Use of Pin hole camera pinhole  camera is used to is to capture the photography AND  movement of the sun over a long period of time. This type of photography is called solography. Pinhole photography is used for artistic reasons, but also for educational purposes to let pupils learn about, and experiment with, the basics of photography.

MIRRORS AND REFLECTIONS

We all use mirrors at home. You look into the mirror and see your own face inside the mirror. What you see is a reflection of your face in the mirror. Sometimes, we see reflections of trees, buildings and other objects in the water of a pond or a lake.

Exercise

1.Rearrange the boxes given below to make a sentence that helps us to understand opaque objects.

OWS

AKE

OPAQ

UEO

BJEC

TSM

SHAD

Solution

OPAQ

UEO

BJEC

TSM

AKE

SHAD

OWS

2. Classify the objects or materials given below as opaque, transparent or translucent and luminous or non-luminous:

Air, water, a piece of rock, a sheet of aluminum, a mirror, a wooden board, a sheet of polythene, a CD, smoke, a sheet of plane glass, fog, a piece of red hot iron, an umbrella, a lighted fluorescent tube, a wall, a sheet of carbon paper, the flame of a gas burner, a sheet of cardboard, a lighted torch, a sheet of cellophane, a wire mesh, kerosene stove, sun, firefly, the moon.

Solution

Opaque	Transparent	Translucent	Luminous	Non-luminous
a piece of rock	Air	A sheet of polythene	A lightened fluorescent tube	A mirror
a sheet of aluminum	Water	Fog	the flame of a gas burner	A piece of rock
A CD	A sheet of plane glass	A sheet of cellophane	a lighted torch	A wire mesh
Smoke			Firefly	Iron
Iron			Stove	A wall
An umbrella			Sun
A wall			Moon

3. Can you think of creating a shape that would give a circular shadow if held in one way and a rectangular shadow if held in another way?

Ans:Yes

4. In a completely dark room, if you hold up a mirror in front of you, will you see a reflection of yourself in the mirror?

Ans:No, in a dark room, a mirror reflection of the image will not be shown as the light will not fall on the mirror to reflect the image.

Name some Transparent objects or materials.

Ans:Air, Water, A sheet of plane glass, etc.

Name some non luminous object or material

Ans:A mirror, Iron, A wire mesh, A piece of rock, etc.

Name some opaque object or material

Ans:A sheet of aluminium , smoke iron etc