Static Electricity on metal sphere

In summary: The rod and sphere become polarised, with the near sides of the two attracting each other. (d) An example of a device using electrostatic charging is a Van de Graaff generator. This device uses a moving belt to transfer charges from a metal comb to a metal sphere, creating a buildup of electric potential energy. The charge is produced through the triboelectric effect, where two materials rubbing together create a separation of charges. The metal comb, which is connected to the moving belt, becomes positively charged while the metal sphere becomes negatively charged. This creates an attractive force between the two, causing the sphere to move towards the comb.
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(b) An uncharged metal-coated sphere hangs from an insulating thread. The sphere is brought
near to the rod. The sphere is attracted to the rod, as shown in Fig. 11.1.

(i) Describe and explain what happens to the free electrons in the metal-coated sphere as it
approaches the rod.
(ii) Draw a diagram to show how charge is distributed on the sphere.
(iii) Explain why the uncharged sphere is attracted to the negatively-charged rod.

(d) Describe one device where electrostatic charging is used. In your answer include a
diagram and explain how and why the charge is produced.
 
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  • #4
Hi DarkPhoenix! :smile:
DarkPhoenix said:

The Attempt at a Solution



(b)(i) Electrons move towards the right since like charges repel.
(ii) Unlike Charges attract. Thus, positive charges from sphere are attracted to rod.

(i) Yes. :smile:

(ii) ah, but surely the negative charges from the sphere are repelled from the rod; and there are an equal number of positive and negative charges; so why doesn't all the attraction and repulsion cancel out? :wink:
 

1. What is static electricity?

Static electricity is a type of electrical charge that is typically created when two objects rub against each other, causing a transfer of electrons. This results in the buildup of an electric charge on the surface of the objects.

2. How does static electricity affect a metal sphere?

Static electricity can affect a metal sphere by causing it to become charged. This can happen when the sphere comes into contact with another charged object or when it is rubbed against another material. The charge on the sphere can also attract or repel other objects, depending on their own charge.

3. What causes static electricity to build up on a metal sphere?

Static electricity can build up on a metal sphere when there is a separation of positive and negative charges on its surface. This can happen when the sphere comes into contact with another object that has a different charge, or when it is rubbed against another material, causing a transfer of electrons.

4. How can static electricity on a metal sphere be discharged?

Static electricity on a metal sphere can be discharged by bringing it into contact with a grounded object, such as the Earth. This allows the excess charges on the sphere to flow to the ground, neutralizing its charge.

5. What are some practical uses of static electricity on a metal sphere?

Static electricity on a metal sphere can be used to attract or repel other objects, making it useful in applications such as electrostatic painting, air filters, and electrostatic discharge (ESD) protection. It can also be harnessed to generate high voltages, as seen in Van de Graaff generators.

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