When performing the following experiments, extend the rubbed objects away from your body so that your body does not influence your observations made with hanging tapes. Also, in humid conditions the electric charge on the pieces of tape can "leak off" causing them to become discharged. You may have to recharge or replace your T- and B-strips from time to time. Create T and B tapes 15 to 20 cm long. Complete the following investigations and record your observations.

Bring charged objects toward the tapes one at a time and record the observations below.

Material T-type tape (Attracted/repelled/Nothing) B-Type tape (Attracted/repelled/Nothing)
Charged area of plastic rod, rubbed with wool
Charged area of glass rod rubbed with silk

Researchers conducted an experiment to identify the effects of three different hand sanitizers on the growth of bacteria. the researchers grew one type of bacteria in twenty-four identical covered petri dishes. then, they opened eighteen petri dishes and applied the three hand sanitizers to six petri dishes each. they left the remaining six petri dishes closed as a control group. when the researchers measured the growth of bacteria two days later, the six dishes that had no hand sanitizer showed the least amount of bacterial growth. the researchers concluded that not using any hand sanitizer would lead to the least bacterial growth. which statement best explains why the researchers’ conclusion was not justified? the experiment tested too many variables. the control group was not treated the same as the experimental group. the sample size of twenty-four petri dishes is not large enough. the single type of bacteria is not adequate to make any conclusions.