Measuring the Speed of Light in Butter

Introduction
Public summary: 

Measure the speed of light using butter and a microwave!

Measure the speed of light
Useful information
Kit List: 

Microwave
Cardboard
Butter/Margarine/Cheap Spread (alt. chocolate, anything melty, wax could work and be reusable?)
Ruler

Packing Away: 

The microwave lives randomly in the cupboard, rulers in the stationary box and everything else is disposable

Frequency of use: 
1
Explanation
Explanation: 

Explain how light is a wave and that microwaves are just some wavelength of this. A microwave has a generator, the nodes and antinodes have different energy levels, the rotation means food gets heated evenly. (aninodes max heat, nodes have no heating bar diffusion)
Remove the turntable from the microwave, this allows us to identify the hotspots. To do so take some cardboard/paper plate and spread a fine layer of spread evenly across it. Place in the microwave for a few seconds. You should notice a pattern in the melted butter, if not keep microwaving it until you see things.
Use the ruler to measure the distance between the hotspots. this gives us half the wavelength of microwaves.
Then speed of light = wavelength * frequency. The frequency of microwaves is around 2.5Ghz.
The speed of light is 29,979,245,800 cm/sec (as you'll probably measure the distance in cm)
For thought how can you improve the accuracy? Choose some other em wave, better generator, deal with reflection inside the microwave.

Risk Assessment
Date risk assesment last checked: 
Thu, 26/12/2019
Risk assesment checked by: 
Tdwebster
Date risk assesment double checked: 
Mon, 20/01/2020
Risk assesment double-checked by: 
Beatrix Huissoon
Risk Assessment: 

don't put foil in the microwave
don't touch the butter while warm
dont put children in microwave
etc....

Hazard Risk Affected Person(s) Likelihood Severity Overall Mitigation Likelihood Severity Overall
Microwave Can cause sparks or explosions if metal microwaved. People shouldn't be microwaved. All 2 4 8 Don't put any objects potentially containing metal or people in the microwave, ever. 1 4 4
Burns Hot things removed from the microwave could cause burns. All 3 3 9 Be careful when removing things from the microwave. Microwave for appropriate time and don't over cook. Ensure children adequately supervised. Allow item to cool before children measure if needed. 2 2 4
Food Contamination Food cooked in the microwave may be contaminated with results of the experiment. Demonstrators 1 2 2 Don't use the microwave for food preparation 1 1 1
This experiment contains mains electrical parts, see separate risk assessment.
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