Light, Shadows and Reflections
Chapter 11
Exercises (অনুশীলনী)
1. Rearrange the boxes given below to make a sentence that helps us understands opaque object.
O W S
A K E
O PAQ
UEO
BJ E C
T S M
SHAD
Ans:-
2. Classify (শ্ৰেণীবিভাগ) 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 aluminium, 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, moon.
Ans:- Opaque:- a piece of rock, a sheet of aluminium, a wooden board, a CD, a wall, a sheet of carbon paper.
Swachhah- Air, water, a mirror, a sheet of plane glass.
Ishat Swachhah: - a sheet of polythene, smoke, polythene.
Radiantman:- a piece of red hot iron, a lighted fluorescent tube, the flame of a gas burner, a lighted torch, kerosene stove, sun, zonaki pigeon, moon.
Lightless:- An umbrella, a cardboard, a wire mesh, a selfen (paper), a piece of stone, an aluminum, a cardboard, a CD, a wall, a single carbon paper.
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:-
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:- In a completely dark room, if we put a mirror in front of us, we will not see any reflection in the room as there is no light source in the room.
Answer By:- Sourabh Bora
