Light and shadows Flashcards
We need light to ______
see
Light can come from many different sources, such as?
Sun, stars, torches, lamps and candles
Light travels ________than anything in the universe and it always travels in ____________.
Faster
straight lines
Which animals are sources of light?
fireflies and glow worms.
_____________
happens inside fireflies and this helps them to light up!
A
chemical reaction
What is an chemical reaction?
chemical reaction
This is when one or more substances react with each other creating a new substance. When you make a cake or bake bread, chemical reactions take place and a new substance is formed.
Something that produces its own light is known as a _____ of light.
source
Fire, lamps and _____ are all examples of sources of light.
stars
Light travels in _____ lines.
straight
Light is the fastest thing in the ______ .
universe
What is a light source?
Something that produces light
Which of these is a source of light? Sun, moon or earth?
sun
How does light travel?
Light travels in straight lines.
When light hits an object, it is
_________
by that object and travels in straight lines to our eyes.
reflected
What is the meaning of ‘‘reflect’’
When something like light, heat or sound bounces off a surface, it is reflected.
Our eyes take in some of this light and information is sent to the _______. This is how we _____ the object.
brain
see
How do we see?
Light travels from the light source to the object where it is reflected into our eyes so we can see.
Some objects such as shiny metal objects _______ light better than dark materials which ________ some of the light.
reflect
absorb
Light rays hit the ball and then ___________ into our eyes.
reflect
What is light?
Energy that zooms around quickly
What is reflection?
Reflection involves a source of light and a surface. The light travels towards the surface and bounces off of it.Mirrors reflect lots of light, but most objects reflect at least a bit of light.
How reflection works?
When light from an object is reflected by a surface, it changes direction. It bounces off the surface at the same angle as it hits it.
Smooth, shiny surfaces such as mirrors and polished metals _______ light well. Dull and dark surfaces, such as dark fabrics, __________ light so they do not reflect it well.
reflects
absorb
In order to see, light will reflect off an object and travel into our ___.
eyes
When the Sun ray hits the black umbrella some of the light is _________ back but some is also ___________ by the dark material.
reflected
absorbed
Which of the following objects reflects the most light?
A black curtain,
Soil or a metal car?
A metal car
When light is reflected by a surface, it ___.
changes direction
What happens when light hits a black wall?
It’s absorbed
Which part of the eye controls how much light enters the pupil?
Iris
What is an shadow and how is it made?
A shadow is a dark shape made when light is stopped or blocked by an object or a person.
Some objects are ________ such as stone, metal and wood. This means light doesn’t travel through them. Light bounces back off the object. On the other side of the object a shadow is formed.
opaque
Why do larger objects produce larger shadows? This is because they block a larger amount of light. If the light source is close to the shadow, this also leads to a larger shadow.
This is because they block a larger amount of light. If the light source is close to the shadow, this also leads to a larger shadow.
Why do some shadows, like the palm trees, change in size?
This is because the distance from the light sources changes
To make a darker shadow, an object has to be ____.
opaque
A shadow is ___ than the object.
darker
When an object is closer to a source of light the shadow is ____.
longer
When a shadow is formed, rays of light ____.
bounce off the object
When an object is further away from a source of light the shadow is ____.
thinner
If an object is __________, it means you can see through the object clearly as light passes through it.
transparent
There are objects that let some light through, but not enough to allow us to see through objects clearly. We call these _______ or _____________
translucent or semi-transparent
Objects that let no light through are __________.
opaque
Shadows are the __________ of light
absence
When an opaque object is placed in front of a light source, it prevents the light from passing through. This
________
of light creates a dark shape on the surface behind it. This is called a __________.
absence
shadow
How can we change the size of shadows?
By moving the position of the light source, we change the size of the shadow.
What happens the closer to the light source gets to an object?
The closer to the light source an object is, the bigger the shadow will be. This is because the object blocks more of the light.
What happens the further away from the light source is away from the object?
The further away from the light source an object is, the smaller the shadow will be. This is because the object blocks less of the light.
What happens when the light source moves directly above an object?
When the light source moves directly above an object, the shadow will be directly below the object.
What will happen when the light source is to one side of the object?
When the light source is to one side of the object, the shadow will appear on the opposite side and the shadow will be longer.
Which kind of object creates the clearest shadow?
Opaque
How can you change the length of a shadow?
Change the position of the object in front of the light
Why are some shadows bigger than others?
Larger objects produce larger shadows. This is because they block a larger amount of light. If the light source is close to the shadow, this also leads to a larger shadow.
Do any shadows change in size?
Some shadows, like the palm trees, change in size. This is because the distance from the light sources changes.
A __________ is a dark shape made when light is stopped or blocked by an object or a person.
shadow
Some objects are ___________ such as stone, metal and wood. This means light doesn’t travel through them. Light bounces back off the object. On the other side of the object a shadow is formed.
opaque
To make a darker shadow, an object has to be ____.
opaque
When an object is closer to a source of light the shadow is ____.
longer
A shadow is ___ than the object.
darker
When a shadow is formed, rays of light ____.
bounce off the object
When an object is further away from a source of light the shadow is ____.
thinner
Light travels in __________.
straight lines
What does it mean if an object is transparent?
If an object is transparent, it means you can see through the object clearly as light passes through it.
There are objects that let some light through, but not enough to allow us to see through objects clearly. We call these ________________
translucent or semi-transparent.
Objects that let no light through are ___________.
opaque
When an opaque object is placed in front of a light source, it prevents the light from passing through. This
absence
of light creates a dark shape on the surface behind it. This is called a ___________.
shadow
What is a shadow?
Shadows are the absence of light
How can you change the size of shadows?
By moving the position of the light source, we change the size of the shadow.
What happens when you move the object closer to the light source?
The closer to the light source an object is, the bigger the shadow will be. This is because the object blocks more of the light.
What happens when you move the object further away from the light source?
The further away from the light source an object is, the smaller the shadow will be. This is because the object blocks less of the light.
What happens when the light source moves directly above the object?
When the light source moves directly above an object, the shadow will be directly below the object.
What happens when the light source is to the one side of the object?
When the light source is to one side of the object, the shadow will appear on the opposite side and the shadow will be longer.
What shape will a shadow look like?
The shape of the object blocking the light
How can you change the length of a shadow?
Change the position of the object in front of the light
Which property of light explains why we have shadows?
It travels in straight lines
We have already learned that the light travels in _________lines. A shadow is formed when light hits an opaque object which stops the rays of light from passing through it. When the object blocks the light’s path, then a dark region appears on the other side. This dark region is called a _________.
straight
shadow
Three basic things are required in shadow formation:
Source of light
Opaque object
Screen or surface behind the object
The center part of the shadow, which gets no light at all, is the darkest region and is called the __________.
umbra
The partial dark region of a shadow around the umbra that gets light from some parts of the source of light is called the _____________.
penumbra
What are the characteristics of a shadow?
Characteristics of shadows
1. Only opaque objects can form shadows.
2. Shadows will always be formed on the opposite side of the light source.
3. Shadow is always black in color.
4. It needs a screen for being formed.
5. The shadow of an object is erect i.e same side up as the object.
6. The size of the shadow depends upon the size of the object, the distance between light source and object and the distance between object and the screen.
7. It is always either large or the same size as that of the object.
What does transparent mean?
Light pass through completely
What does translucent mean?
Light pass through partially
What does opaque mean?
no light pass through
What is an transparent object?
Transparent Object
Objects that allow light to pass through them are called transparent objects. We can see things on the other side of a transparent object by looking through it.
Since this object doesn’t block the light, there is no shadow formation. Sometimes it refers to see-through objects.
For example clear glass windowpane, water, clean air, lense, clear plastics, prism, diamond, etc.
What is an translucent object?
Translucent Object
The objects that allow light to pass through partially are called translucent objects. We can’t see anything clearly that is kept on the other side of a translucent object.
Since this object doesn’t block the light completely, there are faint shadow forms. Sometimes it refers to partially see-through objects. For example, frosted glass, butter paper, tinted glass, wax paper, vegetable oil etc.
