Light and Sight
Explain light and sound as forms of energy
Describe sources and reflectors of light
Task 1
What is light? X
Where does light come from? X
Read SciPad page 74 “Introduction to Energy”.
To answer these questions we need to know about ENERGY.
Can we see and feel energy like we can we feel a substance? X
There are various types of energies. These can be transformed from one type to another.
This is something that seems to be invisible.
It also comes in many forms. Think about a wax candle.
When it is lit a flame gets energy from X
This chemical potential energy is transformed into heat and X energy
Task 2
Do exercises 1 – 3 on SciPad Page 74.
Understand that light travels as an (electromagnetic) waves in straight lines and is independent of matter
Task 3
If you look through a straight tube you can see light from the other side. However, if you bend the tube the light disappears. Why?
X
You cannot see around a corner without the aid of a mirror. This is because light travels in a X.
To represent a light ray you can draw a straight arrow, which indicates the direction in which the light is travelling. The tail of the arrow indicates where the light is coming from.
State the Law of reflection
Most of the light that we see is not direct light. It is light that has been reflected. This is the only time that it changes direction.
Describe sources and reflectors of light
Task 1
What is light? X
Where does light come from? X
Read SciPad page 74 “Introduction to Energy”.
To answer these questions we need to know about ENERGY.
Can we see and feel energy like we can we feel a substance? X
There are various types of energies. These can be transformed from one type to another.
This is something that seems to be invisible.
It also comes in many forms. Think about a wax candle.
When it is lit a flame gets energy from X
This chemical potential energy is transformed into heat and X energy
Task 2
Do exercises 1 – 3 on SciPad Page 74.
Understand that light travels as an (electromagnetic) waves in straight lines and is independent of matter
Task 3
If you look through a straight tube you can see light from the other side. However, if you bend the tube the light disappears. Why?
X
You cannot see around a corner without the aid of a mirror. This is because light travels in a X.
To represent a light ray you can draw a straight arrow, which indicates the direction in which the light is travelling. The tail of the arrow indicates where the light is coming from.
State the Law of reflection
Most of the light that we see is not direct light. It is light that has been reflected. This is the only time that it changes direction.
Task 4
What does the diagram show about the way a ray of light behaves when it strikes a smooth reflective surface?
X
The following diagram shows a ray of light striking a plane mirror.
What does the diagram show about the way a ray of light behaves when it strikes a smooth reflective surface?
X
The following diagram shows a ray of light striking a plane mirror.
Name the missing labels i, ii and iii on the diagram.
i X
ii X
iii X
State the law of reflection.
X
Task 5
Reflection on a curved surface.
Draw what happens to the rays of light when they reach the following mirror.
i X
ii X
iii X
State the law of reflection.
X
Task 5
Reflection on a curved surface.
Draw what happens to the rays of light when they reach the following mirror.
State the Law of refraction
Explain the difference between reflection and refraction
Refraction occurs when a light ray crosses a boundary between two different substances.
It the one substance is more dense or thicker than the other the light will slow down and as a result in the decrease of its speed it will change direction
Task 6
The diagram below shows the refraction of a light ray from air to glass. The incident ray in air is shown.
The refracted ray in glass will change direction towards the normal.
Explain the difference between reflection and refraction
Refraction occurs when a light ray crosses a boundary between two different substances.
It the one substance is more dense or thicker than the other the light will slow down and as a result in the decrease of its speed it will change direction
Task 6
The diagram below shows the refraction of a light ray from air to glass. The incident ray in air is shown.
The refracted ray in glass will change direction towards the normal.
Task 7
Refraction through a lens.
Draw the rays emerging from this convex lens.
Refraction through a lens.
Draw the rays emerging from this convex lens.
Task 8
State the Law of Refraction
X
What is the main difference between reflection and refraction?
X
Describe the nature of white light
Relate colour to the wavelength of light
Explain how a spectrum of colours can be produced by dispersion
White light is split into its component/constituent colours when it passes through a glass prism.
Task 9
What is this phenomenon called? X
Task 10
Draw how the incident white light breaks into the colours of a rainbow or a spectrum when light passes through a glass prism. On your diagram show the order of the colours of the rainbow.
State the Law of Refraction
X
What is the main difference between reflection and refraction?
X
Describe the nature of white light
Relate colour to the wavelength of light
Explain how a spectrum of colours can be produced by dispersion
White light is split into its component/constituent colours when it passes through a glass prism.
Task 9
What is this phenomenon called? X
Task 10
Draw how the incident white light breaks into the colours of a rainbow or a spectrum when light passes through a glass prism. On your diagram show the order of the colours of the rainbow.
Show how primary coloured lights affect each other
Task 11
Three colours of red, blue and green light can be combined to make different colours. Complete the table below to show the colour produced when the given colours on the left are combined.
Red + Blue + Green = X
Red + Blue = X
Blue + Green = X
Green + Red = X
Understand why we see objects as coloured
Colour Subtraction of Light.
A pigment is a substance which absorbs light. Black paint is black because it absorbs all the light colours shone into it. Nothing gets reflected.
The light which enables us to see is usually white light. This is a mixture of all the colours of light.
When we shine white light on a substance then that substance will only appear white if ALL the light colours are reflected.
Usually all of the colours are NOT reflected. This is why a pigment or dye shows a certain colour when white light is shone on it. This is why we say that pigments and dyes SUBTRACT COLOURS OF LIGHT.
If a red light is shone onto a blue paint then you get black because the blue paint can only reflect blue light. The red light will get absorbed. If no light is reflected then you get black.
Task 12
If a green light was shone onto an object containing red pigments and green pigments, what colour(s) would we see the object?
X
Explain in detail why?
X
Understand the structure and function of the human eye
Explain how the human eye works and enables us to see
Task 11
Three colours of red, blue and green light can be combined to make different colours. Complete the table below to show the colour produced when the given colours on the left are combined.
Red + Blue + Green = X
Red + Blue = X
Blue + Green = X
Green + Red = X
Understand why we see objects as coloured
Colour Subtraction of Light.
A pigment is a substance which absorbs light. Black paint is black because it absorbs all the light colours shone into it. Nothing gets reflected.
The light which enables us to see is usually white light. This is a mixture of all the colours of light.
When we shine white light on a substance then that substance will only appear white if ALL the light colours are reflected.
Usually all of the colours are NOT reflected. This is why a pigment or dye shows a certain colour when white light is shone on it. This is why we say that pigments and dyes SUBTRACT COLOURS OF LIGHT.
If a red light is shone onto a blue paint then you get black because the blue paint can only reflect blue light. The red light will get absorbed. If no light is reflected then you get black.
Task 12
If a green light was shone onto an object containing red pigments and green pigments, what colour(s) would we see the object?
X
Explain in detail why?
X
Understand the structure and function of the human eye
Explain how the human eye works and enables us to see
Task 13
Watch the video
http://www.youtube.com/watch?v=gvozcv8pS3c&feature=related
These are the main parts of a human eye.
Retina, Pupil, Optic Nerve, Lens, Tear Duct, Cornea, Iris, Jelly-like Substance, Eyelid, Blind Spot.
Describe the function of the following parts of the eye.
Iris: X
Lens: X
Retina: X
Optic nerve: X
Watch the video
http://www.youtube.com/watch?v=gvozcv8pS3c&feature=related
These are the main parts of a human eye.
Retina, Pupil, Optic Nerve, Lens, Tear Duct, Cornea, Iris, Jelly-like Substance, Eyelid, Blind Spot.
Describe the function of the following parts of the eye.
Iris: X
Lens: X
Retina: X
Optic nerve: X