In a classroom experiment, a student rubs a comb against her hair. The child is then brought near bits of paper resting on a surface. Which of these can be concluded if the comb picks up bits of paper?
A. The comb is an insulator, but paper conducts electricity.
B. The combination had a net charge on it, and it attracted a neutral object.
C. The comb was left uncharged, and it attracted a positively charged object.
D. The comb was positively charged, and it attracted a negatively charged object.
B is the correct answer
If the comb picks up bits of paper, it can be concluded that the correct answer is D. The comb was positively charged, and it attracted a negatively charged object.
To determine the correct answer, we need to understand the phenomenon that is occurring in this classroom experiment. When the student rubs the comb against her hair, it creates friction and causes electrons to transfer from her hair to the comb. This process is known as triboelectric charging.
Now, let's evaluate the given options:
A. The comb is an insulator, but paper conducts electricity.
This option is incorrect because both the comb and the paper are insulators. The transfer of charge is due to triboelectric charging, which does not involve the flow of electricity through a conductor.
B. The combination had a net charge on it and attracted a neutral object.
This option is incorrect because neutral objects are not attracted to charged objects. Charged objects attract neutral objects, but not other charged objects.
C. The comb was left uncharged, and it attracted a positively charged object.
This option is incorrect because the comb itself becomes charged when the electrons transfer from the student's hair to the comb. It does not remain uncharged.
D. The comb was positively charged and attracted a negatively charged object.
This option is correct. When the electrons transfer from the student's hair to the comb, the comb gains excess electrons, making it negatively charged. The bits of paper, being neutral objects, are attracted to the negatively charged comb.
Therefore, the correct answer is option D. The comb was positively charged, and it attracted a negatively charged object.
From Google
When you brushed that comb through your hair, tiny parts of the atoms in your hair, called ELECTRONS, collected on the comb. These electrons have a NEGATIVE charge. ... Then charge your comb again by brushing it through your hair, and bring it close to the tiny pieces of tissue.
Now you choose the correct alternative.