Physical Science 15

You should post which kitchen experiment you will try in the Lab Discussion Forum once you decide - each person should try a different experiment.

Your discussion post about your results is due by Tuesday, 11/18 on Blackboard by 11:55 PM PDT.

Your lab report is due at our next on-campus lab meeting (Wednesday, 11/19 or Thursday 11/20).

Our last (!) home lab offers you two different experiments. The first follows up on last week's interferometry lab with microwaves, allowing you to measure the speed of light in your own kitchen. The second experiment is a bit up to you - there are numerous choices to choose from involving chemistry - and in particular, compounds, and chemical reactions. I've provided a number of websites and ideas for you to consider. I do ask that each of you do a different experiment - so once you decide what you want to try, please POST your intent to try one of the options so others will know to select something else.

Home Lab #2 Part 1: Checking the speed of light!

In last week's lab, you determined the wavelength of microwaves using an interferometer, which takes advantage of the wave nature of light to create an interference pattern that can be measured. This week, it's your turn - if you have a microwave oven!

1. Check out the following website. Try the experiment at home - or work if you don't have a microwave. Toasting and eating the bread afterwards is optional, and extra credit is offered for the best recipes using microwaved buttered bread that was part of your experiment.

Ansell, D. (2008) Measuring the Speed of Light. The Naked Scientists. Accessed 11/3/08 from http://www.thenakedscientists.com/HTML/content/kitchenscience/exp/measuring-the-speed-of-light/

2. Do the experiment! Record the following:

a) The make and model of your microwave.

b) The rated frequency of radiation - be sure to note "GHz" (for Giga-Hertz, or billions of cycles a second) or "MHz" (for Mega-Hertz, or millions of cycles a second.)

c) The approximate length of the microwaves, based on the butter pattern. Also, make an estimate of your uncertainty in this measurement. One good experimental measurement technique that helps to increase precision is to measure the separation between *multiple* bands, and divide by the number of bands. For example, if you found 5 stripes were separated by 10 cm from mid-point to mid-point, the average separation would be 2 cm. Try to measure the distances carefully.

d) Your calculated speed of light, based on the approximate wavelength and frequency of the microwave.

e) Compare your result to the known value, 3x10⁸ meters/second!

Home Lab #2 Part 2:

Rollinson, S. (2006) Kitchen Chemistry. http://personal.cfw.com/~rollinso/SciFood.html

Ansell, D. (2008) Fuzzy Yeast. The Naked Scientists. Accessed 11/3/08 from http://www.thenakedscientists.com/HTML/content/kitchenscience/exp/fizzy-yeast/

Ansell, D. (2008) Fizzes from Peroxide.The Naked Scientists. Accessed 11/3/08 from http://www.thenakedscientists.com/HTML/content/kitchenscience/exp/fizzes-from-peroxide/

Helmenstine, A. Baking Soda & Vinegar Chemical Volcano About.com