General Physics 2 - Electric Charge An electrophorous consists of a plastic base
ID: 1571312 • Letter: G
Question
General Physics 2 - Electric Charge
An electrophorous consists of a plastic base and a metal plate on an insulating handle. The plastic base is rubbed with wool (causes plastic to become negatively charged) and the metal plate is placed on the base. When placed near an electroscope, nothing happens to the 2 pieces of foil hanging in the electroscope. But when touched by a human finger, the foil pieces separate...why?
Similarly, when the plastic base is rubbed with wool, and the metal plate w/insulating handle is placed on it, when you touch the metal base with your finger and place it near the electroscope the foils separate. When you touch the electroscope with your hand, the foils return to their regular positions. When you remove your finger, they remain in their regular position. But once you slowly bring the metal plate away from the electroscope, the foils again separate...why?
Explanation / Answer
An Electrophorous is a device which follows the method of charging by induction.
When the plate base is rubbed with wool, it becomes negatively charged, and the metal plate is placed on the base. When the metal plate is held near the negatively charged plastic base, the electrons within the metal plate will be repelled by the negatively charged plastic base. Hence, positive electrons will be gathered in the lower surface of metal plate and negative electrons will be gathered on upper surface. And when the metal plate is touched by persons finger, the excess charges flow through the finger to the Earth. When the charged metal plate is held near electroscope it attracts opposite charges from the foils towards the top, leaving the foils charged. Then the foils will have like charges, and hence they will repel each other and separate. The foils will have the same charges as the plate.
In second case, When we touch the electroscope with our hand, the charges on foils flows through hand to the Earth, which makes the foil neutral. And so they falls. But when we remove our finger, charges again begins to develop on the foils. And then the metal plate is taken away, which increases the charges and makes the foils charged. And Then foils again separate.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.