ScienceYear 8 Physics

Light

Notes & Experiments

Name:________________Teacher:______________

YOU MUST KEEP THIS BOOK

MY UNDERSTANDING CHECKLIST

[INSERT SCHOOL LOGO HERE]

I can… Textbook page(s)

Before the Topic

After the Topic

Introduction to WavesIdentify a variety of examples of waves we encounter in everyday life 26

Describe how waves transfer energy rather than matter 26

Sketch examples of longitudinal and transverse waves and label on key features (amplitude, wavelength, peak, trough, compression and rarefaction)

26 – 27

ReflectionIdentify the angle of incidence and the angle of reflection 40

Describe how to find the angle of incidence and the angle of reflection 40 – 41

Explain the law of reflection 40 – 41RefractionIdentify the angle of incidence and the angle of refraction -

Describe how a medium affects the speed of a light wave. 42 – 43

Explain how light bends towards and away from the normal as it enters/exits a glass block. 42 – 43

Seeing ColourIdentify the colours in the visible light spectrum in the correct order (link to frequencies) 46 – 47

Describe how dispersion can show that white light is made up of all the colours in the visible light spectrum

46 – 47

Explain how the absorption and reflection of different light frequencies causes us to see different colours.

46 – 47

MY SKILLS CHECKLIST

I can… Before the Topic After the TopicSketch wave diagrams for transverse and longitudinal wavesDraw on the normal to a surfaceBe precise and accurate in my investigations

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KEY WORDS

Some of the key words and definitions are missing some information! Can you complete them?

Key Word Image/Diagram DefinitionAmplitude

The maximum ________ moved by any point on a wave. It is measured from the middle of the wave to the _______ or _______

WavelengthThe length of a wave. It is most easily measured from _______ to _______

FrequencyThe number of ________ per _______

Transverse Wave

A wave in which the vibrations are ________ to the direction of travel.

Longitudinal Wave

A wave in which the vibrations are ________ to the direction of travel.

Ray A beam of light which shows the direction of __________ transfer

Angle of Incidence The angle that the

incoming ______ makes with the _______

Angle of Reflection The angle the

___________ ray makes with the normal.

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NormalA line which is at a _____ ______ to a surface

Reflection When a wave hits a surface and then _________ back.

RefractionThe change in direction of a wave as it passes from one _______ to another

A transparent, solid 3D shape often used in physics experiments

Angle of Refraction The angle the

___________ ray makes with the normal.

A substance that makes possible the transfer of energy from one location to another

DispersionThe spreading out of _______ light to give the visible light ________

Visible Light Light waves than can be detected by the human _____

Spectrum A range of ________ or _______ of light.

AbsorptionTo ‘soak ___’ or ‘take __’

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Lesson 1: Introduction to Waves

DEVELOPING IDENTIFY A VARIETY OF EXAMPLES OF WAVES WE ENCOUNTER IN EVERYDAY LIFE

SECURE DESCRIBE HOW WAVES TRANSFER ENERGY RATHER THAN MATTER

EXTENDING SKETCH EXAMPLES OF LONGITUDINAL AND TRANSVERSE WAVES AND LABEL ON KEY FEATURES (AMPLITUDE, WAVELENGTH, PEAK, TROUGH, COMPRESSION AND RAREFACTION)

SCIENTIFIC SKILLS ABILITY TO SKETCH AND LABEL DIAGRAMS OF TRANSVERSE AND LONGITUDINAL WAVES

Do Now: Draw me a Wave

In the box below, draw the first think that comes to mind when you think of a wave.

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‘A Wave’ by ………………

Teacher Demonstration: The Two Types of Waves

Your teacher is going to show you the two types of wave using a slinky.

A. What were the two types of waves called?

1. ……………………………………….2. ……………………………………….

B. What did the teacher do with their hand to make wave number 1?

C. What did the teacher do with their hand to make wave number 2?

D. What happened when the wave reached the other end of the slinky?

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Science Skill: Labelling Transverse and Longitudinal Waves

Following the teacher demonstration, can you add the correct labels to the following diagrams of a transverse and a longitudinal wave?

PEER MARKING should be done in green pen.

TRANSVERSE WAVE

LONGITUDINAL WAVE

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/4

/2

Investigation: Creating Waves

Working in pairs or three’s, you must complete the tasks and answer the questions. Each group gets 1 slinky.

Task 1 : Create a transverse wave with a large amplitude

A. What movement did you make with you hand? Draw a labelled diagram

B. How would your movement change if you wanted to make the amplitude smaller?

C. Which wave took more energy to create? [Large or small amplitude] Explain your answer.

Task 2 : Create a transverse wave with a short wavelength

A. What movement did you make with you hand? Draw a labelled diagram

B. How would your movement change if you wanted to create a wave with a longer wavelength?

C. Which wave took more energy to create? [Short or long wavelength] Explain your answer.

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Health and Safety Check!

Slinky is prone to tangling.Handle slinky in pairs and only on the floor.

Task 3: Create a longitudinal wave with a long wavelength

A. What movement did you make with you hand? Draw a labelled diagram

B. How would your movement change if you wanted to create a wave with a shorter wavelength?

C. Which wave took more energy to create? [Short or long wavelength] Explain your answer.

Investigation Conclusions

A. All waves transfer energy. Give two ways to increase the energy of a wave1.

2.

In Geometry we use the words parallel and perpendicular to describe the relationship between 2 directions of movement:

B. For the transverse waves did you move your hand parallel or perpendicular to the direction the wave was travelling in?

C. For the longitudinal waves did you move your hand parallel or perpendicular to the direction the wave was travelling in?

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Two movements in the same direction are called parallel.

Two movements at right angles to one another are called perpendicular.

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Use your investigation to draw the following transverse waves

STRETCH

A wave with a shorter wavelength

A wave with a longer wavelength

A wave with a smaller amplitude

A wave with a larger amplitude

Lesson 2: Reflection

DEVELOPING IDENTIFY THE ANGLE OF INCIDENCE AND THE ANGLE OF REFLECTION

SECURE DESCRIBE HOW TO FIND THE ANGLE OF INCIDENCE AND THE ANGLE OF REFLECTION

EXTENDING EXPLAIN THE LAW OF REFLECTIONSCIENTIFIC SKILLS ABILITY TO DRAW THE NORMAL TO A SURFACE

AND USE THIS TO FIND THE ANGLES OF INCIDENCE AND REFLECTION

Do Now: Knowledge and Understanding Quiz

1. Sketch a Transverse wave labelling on the Amplitude, the Wavelength, the Peak and the Trough. [5]

2. A block of wood has a volume of 6cm3 and a mass of 5g. What is the density of the wood? [3]

……………………..

3. Will the above object float? Explain your answer [2]

………………………………………………………………………………………………………………………………………………………………………………………………

4. Name the piece of equipment used to measure current and explain how it should be connected into your circuit? [2]

………………………………………………………………………………………………

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Score [ /11]

Key Fact: The Normal

In physics we sometimes have to add the ‘Normal’ to a surface into a diagram. The Normal is the line which is perpendicular (90o) to the surface of a shape.

We always represent the Normal by a dotted line.

Example:

Worksheet: Add the normal to the surface for each of these ray diagrams

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This is the normal to the top surface of the rectangle

where the ray is hitting it.

Can you make your own weird example?

Investigation: The Reflection Relationship

You teacher will demo how to carry out this investigation.

Can you label the apparatus in the diagram correctly?

METHOD:

1. Join dots 2-5 up to the join between the normal and the plane mirror using a ruler and pencil. [Note dot 1 has been done for you as an example)

2. Line your mirror up with the diagram3. Plug in your light box and switch it on4. Line your light ray up so it follows the line that you drew in step 1. 5. Place 3 crosses, evenly spaced along the reflected ray6. Move away your mirror and light box 7. Use a ruler and pencil to draw your reflected ray and label it ‘1’8. Use your protractor to measure the angle of incidence and angle of reflection,

filling in the table.

PREDICTION:

I think that the angle of reflection will be ____________________________ [greater than /less than/equal to] the angle of incidence.

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cc

Health and Safety Check!

Ray box can get hot duringinvestigation. Switch off when not in use.

RESULTS:

Ray Number 1 2 3 4 5Angle of IncidenceAngle of Reflection

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Investigation: Findings and Conclusions

Use your investigation results to answer the following questions:

1. Which part of the investigation was the hardest?

……………………………………………………………………………………………………………………………………………………………………………………………………

2. Was your prediction correct? [If not; correct it now]

…………………………………………………………………………………………………

3. Why was it important to add the “slit” template to the light box?

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

4. Why did we put crosses on the light rays instead of just using a ruler straight away?

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

5. Complete the following statement:

The Law of Reflection:

The angle of ________ is always equal to the angle of _________

6. Can you suggest any changes to the experiment that would help to make you results more precise?1. ……………………………………………………………………………………………………………………………………………………………………………………………………2. ……………………………………………………………………………………………………………………………………………………………………………………………………

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Reflection is used in ways you may not have thought.

A periscope is used on submarines to help them see above the water when they are underneath. Can you add on the reflected rays to show how this is done?

[Don’t forget your normals!]

Can you think of any other ways that we use reflection if everyday life [not including checking our appearance?]

…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

……………………………………………………………………………………………………………………

STRETCH

Angle incidence incident normal reflected

Lesson 3: Refraction

DEVELOPING IDENTIFY THE ANGLE OF INCIDENCE AND THE ANGLE OF REFRACTION

SECURE DESCRIBE HOW A MEDIUM AFFECTS THE SPEED OF A LIGHT WAVE.

EXTENDING EXPLAIN HOW LIGHT BENDS TOWARDS AND AWAY FROM THE NORMAL AS IT ENTERS/EXITS A GLASS BLOCK.

SCIENTIFIC SKILLS COMPLETE AND INVESTIGATION WITH GOOD LEVELS OF PRECISION TO PRODUCE ACCURATE RESULTS

Do Now: Labelling Reflection

Can you correctly add in the labels to the diagram?

Once you are finished, have a go at filling in the blanks for some of your key words on pages 4 and 5.

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Investigation: What happens to light when it travels through glass?

Your teacher is going to show you how to set up this investigation.

Listen carefully so you can add labels to the apparatus diagram below:

METHOD:

1. Draw around your glass block2. Shine a ray of light into the glass block. Mark its path outside of the block.3. Add a normal where the ray hits the block. 4. Mark the path of the ray inside the glass block. this will be tricky!5. Measure the angle of incidence (between the incident ray and the normal)6. Measure the angle of refraction (between the ray inside the glass and the normal)7. REPEAT the experiment for a range of incident angles.

PREDICTION:

I think that the angle of refraction will be ____________________________ [greater than/ less than/equal to] the angle of incidence.

Useful Animation: https://www.s-cool.co.uk/gcse/physics/properties-of-waves/revise-it/refraction-of-waves

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Health and Safety Check!

Ray box can get hot duringinvestigation. Switch off when not in use.

Results Space: Draw around your glass block below

Attempt Number 1 2 3

Angle of Incidence

[Outside Glass]

Angle of Refraction[Inside Glass]

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Investigation: Findings and Conclusions

Use your investigation results to answer the following questions:

1. Was this investigation easier or harder than reflection? Explain your answer.

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

2. Was your prediction correct? [If not; correct it now]

…………………………………………………………………………………………………

3. What technique did you use to plot the ray of light through the glass block? Was this effective?

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

4. Was the ray of light reflected towards or away from the normal when it went into the glass block?

…………………………………………………………………………………………………

5. Was the ray of light reflected towards or away from the normal when it came out of the glass block?

…………………………………………………………………………………………………

6. Do you notice anything about the rays on either side of the glass block?

…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

So what was happening?

Light changes direction at the boundary when it travels from one material into a different material; this is refraction.

If the light travels from air into any other substance it bends towards the normal.

When light travels into air it bends away from the normal.

This happens because the glass makes the light slow down.

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Refraction can be used to disperse white light.

Using a triangular prism shaped piece of glass (instead of a rectangle), repeat the refraction investigation:

Space for your Results:

Describe what you see happening as the light exits the prism:

………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

STRETCH

Lesson 4: Seeing Colour

DEVELOPING IDENTIFY THE COLOURS IN THE VISIBLE LIGHT SPECTRUM IN THE CORRECT ORDER (LINK TO FREQUENCIES)

SECURE DESCRIBE HOW DISPERSION CAN SHOW THAT WHITE LIGHT IS MADE UP OF ALL THE COLOURS IN THE VISIBLE LIGHT SPECTRUM

EXTENDING EXPLAIN HOW THE ABSORPTION AND REFLECTION OF DIFFERENT LIGHT FREQUENCIES CAUSES US TO SEE DIFFERENT COLOURS.

SCIENTIFIC SKILLS DERIVE IDEAS FROM OBSERVATIONS

Do Now: Knowledge and Understanding Quiz.

1. Sketch and label the path of the ray as it enters and exits the glass block below. [3] [Remember: You must add a normal!]

2. A television is supplied with 650J of electrical energy. It turns 100J of that energy into sound and 15J of energy into light. How much energy is wasted by the television and what form of energy is it? [3]

…………………….. Form: ………………………..

3. Calculate the efficiency of the television. [3]

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Score [ /9]

Demo: Dispersion using a prism.

Your teacher is going to pass a beam of white light through a glass prism.

Write a sentence below to describe what you saw:…………………………………………………………………………………………………..

………………………………………………………………………………………………….

The prism allows us to see that white light is in fact made up of a spectrum of colours. Label the colours and key features to the diagram below:

Sometimes it is good to use a pneumonic to help remember the order of the colours in the spectrum. The pneumonic I am going to use is:

R

O

Y

G

B

I

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The colours of the spectrum are:

R

O

Y

G

B

I

V

Each of these colours has a different frequency.

Investigation: Mixing Colours

When we look around the room we see much more than 7 colours. That is because (like paint) colours of light can mix.

Investigation Aim: To see what happens when we mix the primary colours of light.

Method:

1. You have been given 3 different coloured torches (Red, Green and Blue) – These represent the primary colours of light.

2. To mix the light you have to shine both torches at the same place. 3. Complete the colour chart below to show what colours you see.

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RED

BLUE GREEN

How it Works: Absorption and Reflection

When white light hits an object some of the colours in the spectrum are absorbed while others are reflected.

Examples: NOTES:

Important Fact: When a surface is black no colour is reflected!

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Worksheet: Absorption and Reflection

1. What Primary Colours would be Reflected if an object was:

a. RED:

b. CYAN:

c. MAGENTA:

d. WHITE:

2. What Primary Colours would be Absorbed if an object was:

a. BLUE:

b. YELLOW:

c. GREEN:

d. BLACK:

STRETCH: Coloured filters behave similarly to coloured objects [e.g. If a filter is Red, it will let red light through and absorb all other colours in the spectrum.]

Colour in the Filtered light and explain why no light reaches the eye (only black is seen)

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.

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Figure 1. Joe is in white light. Colour in his clothes.

Figure 2: Joe goes to a disco. The light is red. Colour his clothes the colours they appear now.

Explain the decisions that you have made:

…………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………

……………………………………………………………………………………………………………………

STRETCH

Light: Past Paper Questions

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1

1

1 (b)

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2

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3

3

3

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4

5

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6 (a)

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