Question

select the correct answer.
neville is testing a hypothesis through experimentation. he believes that raising the temperature difference between two water samples will lead to stronger circular currents when the samples are mixed together. which of these actions would be considered a mistake in nevilles experiment?
a. he measures the strength of each current using the same flow meter.
b. he randomly varies the volume of hot and cold water across his trials.
c. he reruns the experiment after fixing calibration problems with his thermometers.
d. he uses glass containers to hold the water samples instead of plastic ones.
e. he states his hypothesis prior to beginning any of his experimental trials.

Explanation:

In a scientific experiment, to ensure valid results, variables should be controlled. The independent variable here is the temperature difference. The volume of water should be kept constant across trials. Randomly varying the volume (Option B) introduces an extra variable, which can confound the results and make it difficult to determine if the change in circular current strength is due to the temperature difference (the variable being tested) or the volume.

• Option A: Using the same flow meter for measuring current strength is a good practice as it ensures consistency in measurement.
• Option C: Rerunning the experiment after fixing calibration problems is appropriate to get accurate data.
• Option D: The type of container (glass vs plastic) is likely not relevant to the circular current strength when the focus is on temperature - difference - induced currents, so this is not a mistake.
• Option E: Stating the hypothesis before trials is a standard part of the scientific method.

Answer:

B. He randomly varies the volume of hot and cold water across his trials.