Science Buddies: "Ask an Expert"

In my experiment( Can The Speed Of Light Be Mesured Through Gelationous Substances?) I am stuck in what else to test. I don't know what other variables can affect the speed of light measurement. Any suggestions? Thanks in advance!

What variables have you tested so far?

well in this experiment i have tested color and thickness and i don't know what else to do

You may want to test electrical resistance or even other parts of the electro-magnetic spectrum beyond visible light (radio, microwave, etc.) to see if there is any variance based on the color, thickness or even opacity (how clowdy it is) of the substance.

Good luck.

What do you mean by thickness? Do you mean literal thickness (e.g. a piece 6 cm thick and a piece 2 cm thick) or the thickness of the liquid (e.g. viscosity). What are you using for your "gelatinous substance"? Are your using Jello or a similar pectin solution? Are you measuring the spped of light through the substance in its liquid form or after the substance has solidified?

If you can answer these questions, I will be able to suggest several variables for you to manipulate.

How are you measuring the speed of light, by index of refraction?

One thing you can try is to dissolve salts of various kinds at different concentrations to change the index of refraction. Even table salt might work. Try some (non-toxic) metal salts such as ferric chloride, which will be yellow.

In this experiment i used both colored jello and clear agar to test the color and literal thicness. Measurements were tested after the jello and agar solidified.

Hi Leilani,

When you dissolved the jello and the agar how much powder and how much water did you decide to use?
Do you think this makes a difference to how many molecules there are in the matrix of your gel?
Do you think this might make a difference to how the light goes through the gel? Does the light go through more easily if there are less molecules or more molecules in its path? (what happened with your thickness experiment might help you answer this)

There have been some good suggestions already about ways you could add some more variables to your experiment but its important to think about what you are trying to test as well and maybe then you could predict what you would see with a new variable.

For example: What do you think would happen if you make the jello with more water or less powder? How would it feel? What happens to the molecules? What do you think will happen to the way the light would go through?

post some of your ideas and we can keep helping,

best of luck
-Caroline

i was wondering if different jello brands have different ingredients

Hi Leilani,

That is an excellent question - yes, different brands can have different ingredients. For example Jell-o brand uses gelatin as a thickening agent, which is an animal product but there are some vegetarian desserts that look the same but have carageenan which is a gelling agent from seaweed. You mentioned that you also tried the gelling agent agar which is another type of seaweed product. Also there might be other ingredients that don't determine the gel consistency of the dessert but could effect the refraction including sugars or artifical sweeteners, colorings, flavorings, stabilzers and preservatives. They should all be listed on the packaging of the product. These are all points to consider in the discussion of your results and planning new experiments.

Best of luck,
Caroline

can you suggest the different types of jello that are for vegetarians.

Hi Leilani,

Do you mean what kinds of thickening agents are suitable for vegetarians, or which brands? I don't know any brand names, you would probably need to go to a supermarket and look at the ingredient lists for that but I can help with what ingredients to look for. Basically geletin is an animal product and ones that use other types of thickening or gelling agents are usually vegeatarian. Those ingredients are things like carageenan, agar, pectin, guar gum, locust bean gum. If you do a search for vegetarian gelatin or vegetarian gelling agents you should be able to find some lists of them and what planst they are made from. Some vegetarian websites may also give lists of brand name jello-type products that are suitable for vegetarians.

Best of luck,
Caroline

Can someone tell me more about the vegetarian gelatin substitute, Irish Moss (Carageen).

Hi Leilani,

I think part of the problem why you didn't find anything is with your spelling - generally the irish moss extract used as vegetarian geletin substitute is spelled carrageenan.

This website looks like a good resource- it has some historical background and then link on the side to the molecular structure.
http://texturant-systems.com/texturant/ ... /carra.htm

Also try google searching for carrageenan or searching wikipedia for information on it.

Good luck,
Caroline

Just to save you some time, here are some of the links that I found:
http://en.wikipedia.org/wiki/Carrageenan

http://www.lsbu.ac.uk/water/hycar.html

http://www.aidsinfo.nih.gov/DrugsNew/Dr ... int_id=400

Hope that helps...
-P