S2/3 BGE Physics Course 1

Unit 1 - Waves and Radiation

1.1 Light

Activity Sheets

Act 1 – Light

YouTube: Bill Nye video – Light and Color (23.00)

https://www.youtube.com/watch?v=g5BHxozBPuA

Answer the following questions while watching the video.

You do not need to write your answers fully in sentences.

Questions

1. What is white light?

2. When white light goes into a prism what comes out?

3. Name the seven colours of the visible spectrum?

4. What colour of liquid is produced when red is mixed with blue?

5. What did the apple do to the light to appear green in colour?

6. What did the boy have on his sign at the sports stadium that the

commentators noticed?

7. Which cloth is warmer in the sun, the white cloth or the black cloth?

8. Which type of light tubes light up signs outside buildings?

9. What are lasers?

10. Why do they put smoke in the air at dance parties?

11. What did the laser burn to show that they are very powerful?

12. When Bill was playing tennis which colours did his white outfit reflect?

13. Why did Bill say that his white car was cool?

14. Where do the colours in the bubbles come from?

15. Why is the sky blue?

Act 2 – Light

Close Reading – Reflection and Refraction - RUAE

Light rays change direction when they reflect off a surface. Light does not

bounce off a surface as the only thing that bounces in Physics is a ball.

The ‘Law of Reflection’ states that, on reflection from a smooth surface,

the angle of the incident ray is equal to the angle of the reflected ray. The

angles are all measured from the normal, which is an imaginary line which

is at 90° to the reflecting surface. This works for flat (plane) mirrors and

curved mirrors.

When light travels from one transparent medium into another, such as air

into glass or air into water, the ray of light will change direction. A normal

line is also drawn at 90° from the boundary between the two mediums,

with the angle of incidence being the angle from the normal in air and the

angle of refraction being the angle from the normal in the non-air medium,

such as glass or water. The speed and the wavelength of the light are

greater in air than in the non-air medium, however the frequency of the

light is the same in both air and the non-air medium.

Applications involving reflection such as looking at yourself in the mirror,

using fibre optic cables where light transfers information from one place to

another in telecommunications and medical systems, are used in

everyday life. A simple application of refraction could involve a visible

spectrum being formed (not a rainbow!!!) and it is also applied in the

formation of optical illusions.

Questions

1) What happens to light rays when they reflect off a surface?

2) State the ‘Law of Reflection’.

3) Where are the angles of incidence and reflection measured from?

4) In refraction, is the angle of light greater in air or in the non-air medium?

5) What happens to the speed and wavelength of light when moving from air into

glass?

6) Which quantity of light is the same in air and any non-air medium?

7) State one application for reflection and one for refraction.

8) Which term must never be used in Physics in relation to the visible spectrum?

Act 3 – Light

Law of Reflection

Aim – To investigate the relationship between the angle of

incidence and angle of reflection using a plane mirror.

Apparatus – Plane mirror, ray box, single slit, power supply

and protractor.

Act 4 – Light

Optical Fibres

Aim – To show that light travels through an optical fibre.

Apparatus – Glass/Perspex fibre shaped block and a laser.

Instructions – Use the block and the laser to show the pattern

above.

What is the light continually doing at each outside surface of

the block?

What are optical fibres made of?

What type of energy is transferred through an optical fibre?

Research Task

Describe in detail how optical fibres are used in everyday

life in telecommunications.

Describe in detail how optical fibres are used in everyday

life in medicine.

Act 5 – Light

YouTube: How a Few Undersea Cables Connect the Entire

Internet (7.04)

https://www.youtube.com/watch?v=eTBLIYJSzdc

1. In which year were ten African countries taken completely off

line for two full days?

2. What caused this communication breakdown?

3. What is the most critical section of the internet?

4. Where does the ACE cable stretch from?

5. Where does the Merea cable stretch from?

6. How many cable faults are found every year?

7. How long do the cables last on average?

8. What is the vast majority of the cables make up actually for?

9. What does the sea plough do in the cable laying process?

10. In which year was the first undersea cable laid?

Act 6 – Light

Lenses

Aim – To investigate the refraction of light in convex and concave

lenses.

Apparatus – Convex lens, concave lens, ray box, triple slit and a

12V power supply.

State the difference found in each lens as the parallel rays of

light pass through them.

Act 7 – Light

Sight Defects

Aim – To investigate long and short sight.

Apparatus – Ray box, triple slit, model eye, convex lens and a

concave lens.

Instructions – Set up the ray box and model eye so that the rays

come to a focus on the retina as shown below.

1. Move the ray box closer to the lens, this is like light from a

close object.

Copy and complete the diagram showing what happens to the

rays.

What sight defect does this show?

What type of lens will correct this defect?

Copy and complete this diagram to show how this sight

defect is corrected.

Lens correction required.

Lens correction completed.

Act 7 – Light (Cont’d)

2. Move the ray box further from the lens, this is like light from a

distant object.

Copy and complete the diagram showing what happens to the

rays.

What sight defect does this show?

What type of lens will correct this defect?

Copy and complete this diagram to show how this sight

defect is corrected.

Lens correction required.

Lens correction completed.

Act 8 – Light

Visible Spectrum

Aim – To show that white light contains a spectrum of colours.

Apparatus – Glass or Perspex prisms, ray box, single slit,

white paper and a power supply.

List the seven colours of the visible spectrum produced.

Act 9 – Light

Colour Mixing

Aim – To show the effect of mixing red, green and blue light.

Apparatus – Ray box, red, green and blue coloured filters, white

screen and a power supply.

Act 10 – Light Skills Activities

1. A pupil recorded the following readings while carrying out a reflection

experiment as shown below with a plane mirror.

The following results were recorded.

Angle of Incidence i (°) 10 20 30 40 50

Angle of Reflection r (°) 9 19 31 41 50

a) Draw a line graph of the Angle of Reflection against the Angle of Incidence.

b) What is your conclusion from the experiment?

2. An experiment was carried out to find the relationship between the focal length

of convex lenses and the power of these lenses. A line graph was then drawn to

show the results of the experiment.

a) Process the graph above by drawing a table of the results recorded.

b) From the graph find the power of a lens of focal length 0.30m.

Act 10 – Light Skills Activities (Cont’d)

3. Light Crossword

Act 11 – Light

Light - Mind Map Summary

Complete the mind map below to organise your thoughts and

knowledge gained in the Light topic.

Light