# How Does Light Travel?

In this worksheet students will be introduced to the topic of light. It defines luminous objects, the speed and direction of light and how shadows are formed.

Key stage:  KS 3

Curriculum topic:   Physics: Waves

Curriculum subtopic:   Light Waves

Difficulty level:

### QUESTION 1 of 10

Light is a form of energy and travels as a wave in straight lines. We see things when light hits them and bounces off and enters our eyes. Objects that create light are sources of light and we call them luminous objects; for example, the sun. We see them because light from them enters our eyes. Light bounces off non-luminous objects (for example, the moon) and we see them because that light enters our eyes once it has bounced off the object.

Light travels faster than sound. We know this because of examples such as thunder and lightning - we see the lightning first and then hear the thunder, but they actually occur at the same time. Another example is dropping an object such as a book - we will see the book hit the floor before we hear the thud. The speed of light is 300 000 km/s (kilometres per second). It takes 8 and a half minutes for light from the Sun to reach the Earth.

When we shine a laser ray (a very narrow beam of light) we can see that light travels in a straight line. Shadows are made because light does not travel through some objects, and so a shadow appears behind these objects (on the opposite side to the light source).

Is the following statement true or false?

Luminous objects create light.

true

false

Complete the sentence by selecting one of the options below:

We can see luminous objects because......

light from them scatters around.

light from them goes to other objects.

light from them enters our eyes.

Complete the sentence by selecting one of the options below:

Non-luminous objects.........

create their own light.

do not create light.

cannot be seen.

Select the two luminous objects from the list below.

sun

wall

table

lamp

Select the two non-luminous objects from the list below.

stars

coffee mug

desk

a candle flame

Which one do we see/hear first: the lightning or the thunder?

we see the lightning first

we hear the thunder first

we see and hear them at the same time

Why do we see/hear them in this order?

light travels faster than sound

sound travels faster than light

they happen at different times

How long does it take for light from the Sun to reach the Earth (in minutes)?

8 minutes

8.5 minutes

85 minutes

What is a laser ray?

a non-luminous object

a narrow beam of light

when light cannot travel through an object.

when light is reflected off an object.

when light travels through an object.

• Question 1

Is the following statement true or false?

Luminous objects create light.

true
EDDIE SAYS
Luminous objects create light, whereas non-luminous objects reflect light.
• Question 2

Complete the sentence by selecting one of the options below:

We can see luminous objects because......

light from them enters our eyes.
EDDIE SAYS
We can see luminous objects because light from them enters our eyes.
• Question 3

Complete the sentence by selecting one of the options below:

Non-luminous objects.........

do not create light.
EDDIE SAYS
Non-luminous objects do not create their own light like luminous ones, light simply bounces off them and into our eyes.
• Question 4

Select the two luminous objects from the list below.

sun
lamp
EDDIE SAYS
The Sun and lamps create light, whereas light would bounce off a wall or a table and into our eyes, enabling us to see them.
• Question 5

Select the two non-luminous objects from the list below.

coffee mug
desk
EDDIE SAYS
Desks and mugs do not create light, but stars and candles both give out light.
• Question 6

Which one do we see/hear first: the lightning or the thunder?

we see the lightning first
EDDIE SAYS
We first see the lightning and then hear the thunder.
• Question 7

Why do we see/hear them in this order?

light travels faster than sound
EDDIE SAYS
Light is faster than sound, so we see the lightning before we hear the thunder.
• Question 8

How long does it take for light from the Sun to reach the Earth (in minutes)?

8.5 minutes
EDDIE SAYS
It takes light from the Sun 8.5 (8 and a half) minutes to reach the Earth.
• Question 9

What is a laser ray?

a narrow beam of light
EDDIE SAYS
A laser gives out a narrow beam of light.
• Question 10

when light cannot travel through an object.
EDDIE SAYS
A shadow is formed when light cannot travel through an object. Opaque objects form shadows.
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