Static Electricity: Charging Objects with Friction, Induction, and Conduction

[Kylah]

1. Name three methods that could be used to charge an object.
Friction, induction, and conduction, I assume...


2. A negatively charged rubber rod is momentarily touched to the knob of a neutral electroscope and then removed.
A) What is the charge on the knob? Negative
B) What is the charge on the leaves? Negative
C) What is this method of charging called? Conduction
D) What happens to the leaves? They scatter.
E) How could you prove that the electroscope has a negative charge? If it is attracted to a positively charged object, then you know it's negatively charged.

3. A positively charged glass rod is held near the knob of a neutral electroscope.
A) Wht is the charge on the knob? Negative
B) What is the charge on the leaves?Positive
C) What is this method of charging called? Induction
D) Explain why what happens to the leaves. They'll repel each other.
E) Explain what happens if the knob is now grounded. It loses it's charge.
F) Explain what happens to the electroscope if the ground is removed and the glass rod is removed. No idea.

Can anybody tell me if my answer look right or not? And hopefully guide me in the correct direction if they're wrong. Also, I really have no idea for 3f... so any help would be greatly appreciated.

The Attempt at a Solution

 

[jbsteele]

:A) What is the charge on the knob? PositiveB) What is the charge on the leaves? PositiveC) What is this method of charging called? InductionD) Explain why what happens to the leaves. They will be attracted to each other because they both have the same charge.E) Explain what happens if the knob is now grounded. The electroscope will lose its charge and be neutralized.F) Explain what happens to the electroscope if the ground is removed and the glass rod is removed. The electroscope will then be left with a positive charge, as the glass rod transferred its positive charge to the electroscope when it was near it.

 

[Moetasim]

1. The three methods that could be used to charge an object are friction, induction, and conduction.

2. A) The charge on the knob is negative.
B) The charge on the leaves is also negative.
C) This method of charging is called conduction.
D) When the negatively charged rubber rod is touched to the knob, the electrons from the rod transfer to the knob, giving it a negative charge. The leaves of the electroscope, being negatively charged, will repel each other and scatter.
E) To prove that the electroscope has a negative charge, you can bring a positively charged object near it. If the leaves are attracted to the positively charged object, it indicates that the electroscope is negatively charged.

3. A) The charge on the knob is still negative.
B) The charge on the leaves is now positive.
C) This method of charging is called induction.
D) When the positively charged glass rod is held near the knob, the electrons in the leaves are repelled, causing them to spread apart and become positively charged.
E) If the knob is now grounded, the excess electrons in the leaves will flow to the ground, leaving the electroscope with no net charge.
F) When the ground is removed and the glass rod is also removed, the leaves will return to their original position, as the excess electrons have been redistributed.