The Speed Of Light From Your Microwave - Revision history

imported>Stwikiadmin at 18:21, 19 July 2016

2016-07-19T18:21:17Z

imported>Stwikiadmin at 18:48, 13 July 2016

2016-07-13T18:48:31Z

← Older revision		Revision as of 18:48, 13 July 2016
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			<!--
			{\| class="wikitable" style="color:black; background-color:#ddd; margin-left: auto; float:right"
			\| [[Astronomy]], [[Physics]]:
			\| The Electromagnetic Spectrum, Speed of Light
			\|-
			\| Grade Range:
			\| [[Elementary School]], [[Middle School]], [[High School]]
			\|-
			\| Format:
			\| [[Hands-on]], [[Stage]]
			\|}

			This demonstration provides kids with a simple and sticky way to measure the speed of light on their own. Be sure to have a way to dispose of the marshmallows before performing this demonstration.

			== Materials ==

			* Microwave
			* Marshmallows
			* Microwave Safe 8x8 Baking Dish
			* Ruler
			* White Board & Markers (Stage)
			* Paper & Pencils (Hands-on)

			== Safety Precautions ==

			Please read the General Safety Precautions section of the [[Demonstration Safety]] page before performing this demonstration.

			== Demonstration ==

			;Presentation (Stage):
			# Announce to the audience that you can calculate the speed of light using marshmallows and a microwave. Ask the audience if they have heard of the electromagnetic spectrum. If they have, ask them what it is, and what kinds of waves are on the spectrum.
			# Put a single file line of marshmallows on the baking plate, being sure that they fill the dish. Remove the turntable from the microwave, and set the baking dish in so it won't turn. Microwave the marshmallows for 1-2 minutes, or until you see a standing wave pattern in the marshmallows. Remove them from the microwave and point out the wave pattern to the audience.
			# Use the ruler to measure half a wavelength, and look up the microwaves frequency on the back of the unit. Write both numbers on the board with their units, with wavelength in cm and frequency in hertz or 1/s. Multiply the numbers together, and you should get a number close to the actual speed of light, 3 * 10<sup>8</sup> m/s!

			;Presentation (Hands-on):
			#

			== Why This Works ==

			===Short Explanation===
			This is where you would provide a basic, easy-to-understand explanation of the demonstration. Try not to use too much "Science Jargon", and if needed add any explanation tips, like comparing the demo to something kids are familiar with.

			===Full Explanation===
			This is where you will explain the demonstration in full, and provide all additional information that pertains to the demo. Unlike the short explanation above, this should be worded so someone who is familiar with the topics might understand it. If needed, you can provide equations and citations for additional sources of information on the topic. This is also where you will find some answers for trickier questions, such as "How does a plane fly upside-down?" for the Bernoulli's Principle demo. If you want to add a floating box for equations, copy the following:

			{\| class="wikitable" style="color:black; background-color:#ddd; text-align: center; margin: auto"
			\| This will give you
			\| a floating box.
			\|-
			\| The box will be
			\| centered for you.
			\|}

			== Additional Information ==

			* Any extra tidbits that do not fit into other sections
			* This demonstration is a part of the (insert [[Stage Show]] here)
			-->
	== Age ==		== Age ==

imported>Stwikiadmin: Created page with "== Age == Elementary School, but better for Middle School, High School == Format == Hands-on == Materials == Microwave Marshmallows (1/2 bag) 8x8 baking dish ..."

2013-09-12T01:00:47Z

Created page with "== Age == Elementary School, but better for Middle School, High School == Format == Hands-on == Materials == Microwave Marshmallows (1/2 bag) 8x8 baking dish ..."

← Older revision		Revision as of 01:00, 12 September 2013
(No difference)

imported>Stwikiadmin: Created page with "== Age == Elementary School, but better for Middle School, High School == Format == Hands-on == Materials == Microwave Marshmallows (1/2 bag) 8x8 baking dish ..."

2013-09-12T01:00:47Z

Created page with "== Age == Elementary School, but better for Middle School, High School == Format == Hands-on == Materials == Microwave Marshmallows (1/2 bag) 8x8 baking dish ..."

New page

== Age ==

Elementary School, but better for Middle School, High School

== Format ==

Hands-on

== Materials ==

Microwave
Marshmallows (1/2 bag)
8x8 baking dish
Ruler
Calculator
Electromagnetic spectrum poster
Wave/speed of light poster

== Safety Precautions ==

Science Theatre demonstrators must keep the safety of themselves and their audience in mind at all times. All Science Theatre demonstrators must have read through the Safety Training page. The ST Safety Box with first aid kit, fire extinguisher, etc. should always be available to demonstrators. Always wear safety gloves, glasses, and a labcoat if handling chemicals; always perform potentially dangerous demonstrations at a safe distance from the audience; and always keep a very close eye on any volunteers you call from the audience.

Don’t eat the marshmallows.

== Preparation ==

Remove the revolving plate from the microwave. Note the frequency of the microwave from a label on the back.

== Demonstration ==

Place the marshmallows in the baking dish so that they stand side by side and fill the dish. Place the dish inside the microwave, butted up against a corner. Microwave the marshmallows for 1-2 minutes, until a standing wave in the marshmallows can be seen. Remove the dish, measure the wavelength of the standing wave. Multiply the wavelength of the wave (in meters) by the frequency on the back of the microwave (in hertz (1/s)), this will give you the speed of light. The actual speed of light is 3 x 108 m/s, you should get something on the right order of magnitude.

== What to Say ==

Before starting, explain to the audience what a wave is, including what a wavelength is and how it can be measured. Start by asking the kids where they have seen a wave (the ocean). In the ocean, only the positive portion of the wave is seen. You will most likely have to measure a half a wavelength, so explain that each portion of the wave is equal, and you can just multiply the half a wavelength by two to get the entire wavelength although it is not visible in the marshmallows.

Next, explain where microwaves lie in the electromagnetic spectrum. Visible light is only a small portion of the electromagnetic spectrum, and the wavelengths of visible light are extremely small compared to the wavelengths of microwaves.

Light travels with a speed called the speed of light. This is 3 x 108 m/s or approximately 186,282.397 miles per second (mention this number). In order to calculate the speed of light from the microwave, the wavelength of the microwaves from the appliance must be measured and multiplied by the frequency on the back of the appliance. The frequency is how many microwaves are emitted per second, and has units of ‘per second.’

The microwaves in the appliance will affect the marshmallows according to where in the wave the marshmallows lie. This will produce a ‘wave’ in the marshmallows which is the same size as the microwave.

== Why It Is ==

The speed of light is 3 x 108 m/s, that is, light travels 300,000,000 meters in one second. Light is a wave, and travels as a wave. By measuring the length of the microwaves in the appliance and using the frequency from the manufacturer, the speed of light can be approximated from the standing wave in the marshmallows.

==Real Life Examples ==

Waves in the ocean. Also, you can mention that since the light from lightning travels so fast, it takes some time for the thunder to catch up (~5 sec/mile).