2.4.1 - 2.4.1 - Electric charge

Question 1

What are the 3 small particles contained in an atom

Answer 1

protons, neutrons and electrons

Question 2

Which particles are found in the centre of the atom (nucleus)

Answer 2

Protons and neutrons

Question 3

What is the relative charge of protons

Answer 3

+1

Question 4

What is the relative charge of neutrons

Answer 4

neutrons do not carry a charge

Question 5

Where are electrons in relation to the atom?

Answer 5

electrons travel around the nucleus in orbit

Question 6

What is the relative charge of an electron

Answer 6

-1

Question 7

Why does an atom not have an overall charge

Answer 7

Normally the number of protons and electrons are the same protons have a positive charge electrons have a negative charge so no overall charge

Question 8

What happens if an atom looses an electron

Answer 8

it becomes positively charged

Question 9

What happens if an atom gains electrons

Answer 9

it becomes negatively charged

Question 10

What is an atom called that becomes charged by gaining or loosing electrons

Answer 10

An ion

Question 11

What are the factors that effect how an object can be charged by rubbing

Answer 11

Must be made from different materials, these materials must be electrical insulators

Question 12

What are electrical conductors

Answer 12

Materials or substances that allow the free flow of electrical current this is because they have many delocalised electrons that can pass on the current

Question 13

What are electrical insulators

Answer 13

A material or device that does not allow electrical current to flow easily because hey have very few delocalised electrons

Question 14

Examples of good electrical insulators

Answer 14

Plastic, rubber, glass wood

Question 15

Explain Investigate how insulators can become electrically charged by friction

Answer 15

It can be shown how insulating materials can be charged by friction using an uncharged plastic rod and an uncharged cloth. First make sure they are not already charged by placing them near paper making sure they are not already attracted. No charge No attraction. Then rub the cloth and rod together for a few seconds and then place the rod next to another rod and there should be an attraction retest them because they are made from different materials they should be charged.. Can repeat this experiment using electrical insulators.

Question 16

Explain cloth rod experiment

Answer 16

When the uncharged plastic rod is rubbed with an uncharged cloth, electrons from the atom of the rod move onto the cloth. There is now an unequal number of positive and negative charges on each. The rod has lost electrons so it has become positive. The cloth has gained electrons so it is now negatively charged.

Question 17

How do charged objects exert forces on each other

Answer 17

If the charged objects have the same charge they repel but if the objects are oppositely charged they attract each other.

Question 18

How does the balloon experiment show that an object that is charged can attract and object that is uncharged

Answer 18

If you charge a balloon by rubbing it against your jumper and then hold the balloon against a wall the balloon will stick to the wall. Because there is an attraction between the charged balloon and the uncharged wall. The balloon is negatively charged and the wall is uncharged same number of positive and negative charges. As the negatively charged balloon is brought closer to the wall some of the negative electrons are repelled from the surface of the wall. This gives the surface of the wall a slight positive charge that attracts the negatively charged balloon

Question 19

Explain the ruler paper experiment

Answer 19

using a plastic ruler and some small pieces of paper. Rub the plastic ruler against the sleeve of your jumper. The ruler will become charged. if it is held close to some small uncharged pieces of paper the electrons within the paper will be attracted to the edges closest to the ruler there will be an attraction between these negative parts of the paper and the positive ruler.

Question 20

How does static electricity relate to spray painting

Answer 20

Spray painting an object like a bicycle frame or a car with a spray gun can take a long time so using electrostatic spraying can make the process much more efficient. As the drops of paint emerge from the spray gun they are charged. As the drops carry the same charge they repel and spread out forming a thin spray. The metal bicycle frame has a wire attached to an electrical supply giving the frame the opposite charge. The paint drops are therefore attracted to the surface of the frame.

Question 21

Explain how static electricity works in inject printers

Answer 21

Many modern inkjet printers use inkjets to direct a fine jet stream of ink drops onto paper. They do this by using electrostatic forces. Each spot of ink is given a charge so that as it falls between a pair of deflecting plates, electrostatic forces direct it to the right position. The charges on the plates change hundreds of times per second so that each drop falls in a different position, forming pictures and words on the paper as required.

Question 22

Explain the stages of static electricity on photocopiers

Answer 22

1) Drum is charged
2) Image of object to be copied is formed here charges stay only where the image is dark
3)Toner drops on to drum and sticks to charged areas
4) Surplus toner is removed
5) paper is pressed against toner image to give image on paper
6)paper is heated to melt toner image this forms permanent image on paper

Question 23

Explain how static electricity works on photocopiers?

Answer 23

Positive charged are sprayed onto a turning drum whose surface is covered with a metal called selenium (metals good conductors of electricity) A bright light is shone onto the sheet of paper to be copied. The white parts of the paper reflect light onto the drum, The dark or printed parts do not. In those places where light is reflected onto the drum the selenium looses its charge but where no light is reflected onto the drum the charge remains. Toner is blown across the drum and sticks to just those parts of the drum that are charged. A sheet of paper is now pressed against the drum and picks up the pattern of the toner. This toner is then fixed in place by a heater

Question 24

Explain how electrostatic precipitation works in static electricity?

Answer 24

-Many heavy industrial plants produce large quantities of smoke. This smoke carries small particles of ash and dust into the environment. One way to remove these pollutants from the smoke is to use electrostatic precipitators
-As the smoke rises up the chimney it passes through a mesh of wires that are highly charged. As they pass through the mesh they become negatively charged. higher up the chimney these charged particles are attracted by a stick to large, metal earth plates which are positively charged. Cleaner smoke is released into the atmosphere and the rest it waited unit, it is full and tapped into boxes

Question 25

What are some of the problems with static electricity?

Answer 25

As aircraft fly through the air, friction causes them to become charged with static electricity. After an aircraft has landed there is the possibility of charges escaping to earth as a spark of flash or electricity. If this takes place during refuelling, it can cause an explosion. The solution to this problem is to earth the plane with a conductor as soon as it lands before refuelling allowing the charge that is built u[ to flow to the earth. Fuel tankers the transport fuel must also be earthed before any fuel is transferred to prevent sparks causing a fire or explosion

Question 26

Explain another problem of static electricity?

Answer 26

Sometimes after a long car journey a person can be charged with static electricity and when we step from the car we might receive a small electric shock. Our clothing has been charged with static electricity when removing the clothes there is also a chance of receiving a small electric shock

Question 28

Examples of good electrical conductors

Answer 28

Graphite, metal copper, tin, and gold