Explaining the Phenomenon of Static Electricity

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When a comb is rubbed against a sweatshirt, it gains electrons and becomes negatively charged. The tissue paper remains neutral but is polarized by the electric field of the charged comb, resulting in a net attractive force. The positive charges in the tissue paper are drawn closer to the negatively charged comb, leading to attraction. This interaction exemplifies static electricity, where opposite charges attract. The charges are temporary and will eventually dissipate, making this a clear demonstration of the principles of static electricity.
chase222
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Tomorrow I have to do a demo in physics regarding static electricity. I am going to rub a comb against the inside of my sweatshirt and then attract tissue paper to it. I don't understand how to explain why this happens.

Is the comb neutral at first, then when you rub it to the sweatshirt it gains electrons and has a negative charge? Is the tissue paper a positive charge because opposites attract? Please explain this to me if I am wrong. Thanks!
 
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chase222 said:
Is the comb neutral at first, then when you rub it to the sweatshirt it gains electrons and has a negative charge?
That's right.
Is the tissue paper a positive charge because opposites attract?
The tissue paper is neutral (no net charge), but the field from the charged comb polarizes the atoms in the paper. Since the positive charges in the paper are closer to the negative comb than the negative charges are, there is a net attractive force (called a polarization force) between the paper and the comb.
 


You are on the right track! When you rub the comb against your sweatshirt, the comb gains electrons from the sweatshirt, giving it a negative charge. The tissue paper, on the other hand, has an overall positive charge. This is because the atoms in the tissue paper have a slightly higher number of protons than electrons, making it positively charged. Opposites do attract, so the negatively charged comb will attract the positively charged tissue paper. This phenomenon is known as static electricity, where objects with opposite charges are attracted to each other. The transfer of electrons from one object to another is what causes this attraction. It's important to note that the charges are temporary and will eventually dissipate, but it's a great way to demonstrate the principles of static electricity. I hope this helps and good luck with your demo tomorrow!
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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