Light Energy

Question 1

Light does not require a __________ to travel

Answer 1

Medium

Question 2

Any object that produces light is known _____________

Answer 2

Source of light

Question 3

What are the two types of light sources?

Answer 3

Natural light source and artificial light source

Question 4

What is natural light source? Give an example

Answer 4

Natural light source exist in nature on their own. Ex: sun

Question 5

What is artificial light source? Give an example

Answer 5

Light sires that are man made. Ex: candles, electric bulbs

Question 6

What is a luminous object?

Answer 6

Objects that give out light of their own are called luminous objects

Question 7

What are non-luminous objects?

Answer 7

Objects that do not give out light of their own are called non-luminous object

Question 8

What is bioluminescence

Answer 8

The production of light by a living organism as a result of some chemical energy getting converted into light energy is called bioluminescence

Question 9

Give examples of bioluminescent objects

Answer 9

Fire flies, jellyfish

Question 10

Why is moon a non-luminous object? Give reason

Answer 10

Moon does not have any light of its own. It’s light is refracted from the sun

Question 11

What are greenhouses

Answer 11

Structures built with glass or transparent plastic for growing plants

Question 12

What is a transparent medium? Give examples

Answer 12

A medium that allows most of the light to pass through it is called transparent medium. Ex: clear glass, Clear water

Question 13

What is translucent medium? Give examples

Answer 13

A medium that allows only a part of the light to pass through it is called translucent medium. Ex: butter paper, fog

Question 14

What is opaque medium? Give examples

Answer 14

A medium that does not allow any light to pass through it is called an opaque medium

Question 15

Define rectilinear propagation of light

Answer 15

The property of light travelling in straight lines in a medium Is called the rectilinear propagation of light

Question 16

What do you mean by principle of least time?

Answer 16

Light takes a path that requires the shortest time is called the principle of least time

Question 17

What is ray of light?

Answer 17

It is a path along which light energy travels

Question 18

What is beam of light? What are it classifications?

Answer 18

A group of rays of light is called a beam of light. A beam of light is classified into 3 types namely; parallel, convergent, divergent.

Question 19

What is parallel beam of light?

Answer 19

A group of parallel rays of light is called parallel beam of light

Question 20

What is convergent beam of light?

Answer 20

When rays of light from different directions converge at a point, the collection of rays is called a convergent beam of light

Question 21

What is a divergent beam of light?

Answer 21

When rays of light from a point diverge in different directions, this collection of rays is called a divergent beam light

Question 22

What is the speed of light?

Answer 22

3 x 10 to the power of 8 m/s

Question 23

Explain the formation of shadows

Answer 23

When the light rays are stopped by an object, a dark region forms behind the object, this dark region is called a shadow

Question 24

What are the characteristics of shadows?

Answer 24

1. Formed only in the presence of light
2. Always formed on the source of light

Question 25

What does the position of the shadow depend on?

Answer 25

It depend on the size one position of both the object and the light source

Question 26

What is an umbra?

Answer 26

The darkest part where no light falls at all is called the umbra

Question 27

What is a penumbra?

Answer 27

It is the region of partial darkness