Question

a student is measuring the effects of an electric circuit on a compass, and he is testing to see if increasing the current will cause the compass needle to change its direction faster. he does one trial using a 9-volt battery and another trial using a 1.5-volt battery. he takes accurate data.

based on good experimental design, what would improve his experiment?

○ he should add a nonworking compass to act as a control.
○ he should use only one battery but do several trials, using different circuit designs to ensure he has appropriate test groups.
○ he should repeat the test with three additional batteries of varying voltages to demonstrate the reproducibility of results.
○ he should use batteries of the same voltage but from different manufacturers to show he has used different variables.

Explanation:

Answer:

He should repeat the test with three additional batteries of varying voltages to demonstrate the reproducibility of results.