Light waves

...light waves...

Objectives:

Pretty colours.

• Know that f

• Be able to w

Task 1 - Starter

Hands up!

I know the answer!

Find someone who knows:

1) How we could make a transverse wave on a rope.

2) How we could make a longitudinal wave on a helical slinky spring.

3) How a loudspeaker produces sound waves.

4) The frequency range of human hearing.

5) The colours of the visible spectrum.

6) The primary colours of light.

7) The secondary colours of light.

Your teacher will tell you which questions to answer. The simulations below might help to remind you about some of these concepts.

Simulation - transverse waves

The simulation below allows you to investigate the characteristics of a wave on a string.

Set to oscillate, no end and no damping. Investigate how changes to the frequency and amplitude change the appearance of the wave.

Click the image below to load the simulation in full screen mode instead.

Click to Run

Thanks to PhET for this awesome simulation :)

HTML5 technology! Woop Woop!

Flash version available too. Click here to load.

Simulation - longitudinal waves

The simulation below shows a longitudinal wave - in this case, sound waves travelling through the air.

Click the image to load the simulation.

1. Select wave type "sound" (2nd tab).

2. Expand the particle area with the green "+" sign.

3. Select "particle view" with the radio buttons.

Click to Run

There is copy of this simulation stored on the local server here.

Thanks to PhET for this awesome simulation :)

Java technology! Woop Woop!

Simulation - colour mixing

The simulations below shows how different colours of light mix together.

Teacher note: click here for a full-screen version.

Investigate the additive mixing of colours. Simulation credit: PhET.

Visit http://phet.colorado.edu/

Flash technology!

Task 2 - Filters

Lots of filters.

Coloured fi

lters!

Mixing colours of light.

Coloured filters allow some colours of light to pass through, but not others.

Your teacher will show you how filters can be used to produce different colours of light from a ray box, and how the light is affected when it passes through other filters.

Your teacher will show you what happens when cyan light passes through a yellow filter.

What colour light is produced? Can you work out why?

Diagram - cyan light and yellow filter

Complete the diagram!

What will happen when the cyan light from the ray box hits the yellow filter?

Remember that light travels in straight lines!

Note: this diagram is available here as a word document.

Complete the text

Fill in the missing words:

The primary colours of light are _________, __________ and __________. White light contains all three of these colours. If we pass white light through a cyan filter, only the __________ and __________ light can pass through the filter; the _________ light is absorbed by the filter.

A yellow filter only allows ___________ and _________ light to pass through. If we pass cyan light through the yellow filter, only the ________ light can pass through; the _________ light is absorbed by the filter.

This text is available here as a word document.

Task 3 - Predictions

You are going to investigate how different colours of light are affected by different filters.

Predict the outcome of each scenario first. Your teacher will help you to work out a few, as examples.

This table is available here as a word document.

Task 4 - Investigating filters practical work

Ray box and filters.

Colour

Use your ray box and filters to investigate each of the combinations in your table.

• Were your predictions correct?

• Were there any unexpected results?

Extension task: Think of your own combination(s) to try. Predict what will happen, and then try it out to see if you were correct!

Task 5 - Plenary

Think hard!

Different coloured objects can appear surprising colours when viewed under coloured lights. Your teacher will show you some demonstrations. Can you explain what is happening in each case?