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Science Buddies experiment “how blue is my sports drink”

Postby BigMomma44012 » Tue Jan 05, 2021 12:41 pm

We are doing one of your science projects posted on the website(How blue is your sports drink)

In your results section it says:

Calculate the average for your three resistance readings for each standard. Subtract the resistance that you measured for the blank from all of the readings you made for samples with dye. This step subtracts the light loss due to the plastic, the water, and other factors.

My question is do I need to subtract the resistance from the samples also?

Thanks for the advice.

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Re: Science Buddies experiment “how blue is my sports drink”

Postby probiotics » Tue Jan 05, 2021 7:08 pm


I'm glad to hear that you are using Science Buddies resources for you science fair needs! This is a very interesting project.

To answer your question, yes, you do need to subtract the resistance from the samples as well!

Think of it like a scale - if we need to measure out some powder on a scale, it wouldn't be possible to put the powder directly on the scale. Instead, we would place a plate on the scale and then zero the scale. Zeroing the scale essentially means that the value displayed on the scale will be set to zero regardless of what is on top of the scale. Now, when you add the powder to the scale, the weight displayed on the scale only represents the weight of the power!

In a similar manner, when we use the spectrophotometer, we need to account for the water, the plastic, and other factors that would affect our readings. The methods states to subtract the resistance from all readings made for samples that contains the dye, which would also include the sport drinks samples. If we didn't subtract the control resistance from all other readings, there would be a bias in your data as the calibration curve results would not match up with the sport drink sample results.

Hope this helps!

Thanks, probioitcs

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