Electrostatics

Question 1

What are the two types of charge

Answer 1

Positive charges namely protons and negative charges namely electrons.

Question 2

What Is tribo electrical charge

Answer 2

The process by which electrons are transferred when two objects come Into contact with each other and are then separated from each other. During the process of tribo electrical charge, one object wins electrons on its surface and is charged negatively, the other object loses electrons from its surface and is positively charged

Question 3

What does the word tribo mean

Answer 3

To rub

Question 4

What is the tribo electrical series

Answer 4

The tendency of a substance to either give up electrons and be positively charged or take up electrons and be negatively charged

Question 5

What are the substances on the tribo electrical series

Answer 5

Dry skin human 
Rabbit fur 
Perspex 
Cellulose acetate 
Glass
Human hair 
Nylon 
Wool 
Cat hair 
Flannel 
Silk 
Paper 
Cotton (neutral) 
Steel  (neutral) 
Wood  (neutral) 
Ebony 
Rubber ballon 
Stiff rubber 
Nickel, copper, silver 
Foam plastic 
Cling plastic 
Polythene 
Polyethylene (scotch tape)
Vinyl (PVC) 
Silicone

Question 6

What are the factors that influence electrostatic forces

Answer 6

Distance and magnitude of the charges

Question 7

What is an electrostatic force

Answer 7

À force of attraction or répulsion between two charged objects

Question 8

What is electrostatics

Answer 8

The study of charges at rest

Question 9

What does matter consist of

Answer 9

Atoms or molecules which contain equal numbers of protons and electronS

Question 10

How can insulators be charged

Answer 10

Through friction

Question 11

How do positive ions form

Answer 11

Through the loss of electrons

Question 12

How do negative ions form

Answer 12

Through the gaining of electrons

Question 13

What will like charges do

Answer 13

Repel

Question 14

What will unlike charges do

Answer 14

Attract

Question 15

What is the law of conservation of electrical charge

Answer 15

Charges cannot be created or destroyed, but separated and transferred from one object to another. Therefore we say that the net charge of an isolated system remains constant

Question 16

What is the unit of charge

Answer 16

Coulomb (C)

Question 17

What is the elementary charge

Answer 17

The charge of an electron

Question 18

What is the charge of an electron

Answer 18

-1,6 x 10^-19

Question 19

What is the charge of a proton

Answer 19

1.6 x 10^-19

Question 20

How do charges objects attract uncharged insulators (since their electrons cannot move freely)

Answer 20

a charged object attracts or repels an uncharged object to form a slightly negative pole and slightly positive pole on an object due to the movement of electrons from one side of the atoms in the object to another (to shield positive charges or unshield the positive charges. This is called a temporary dipole. Because this process takes place due to the proximity of an external charge we call this induced polarisation

Question 21

How do charged objects attract uncharged conductors

Answer 21

A charged object repels or attracts the electrons of the conductor leaving an excess positive charge or excess negative charge which is then attracted by the charged object

Question 22

What is a permanent dipole

Answer 22

When the arrangement of electrons in a molecule is uneven resulting in a slightly positive and slightly negative side even though the molecule as a whole is still neutral

Question 23

Why are objects that are charged mounted onto an isolated stand during an experiment

Answer 23

So that the charges on the object do not become grounded

Question 24

What is the symbol for electrical charge

Answer 24

Q or q

Question 25

What is the equation for the charge when 2 identical size conductors come into contact

Answer 25

qnew = (q1 +q2)/2

Question 26

What is the formula to determine the charges transferred

Answer 26

(Delta)q=qf-qi

Question 27

What is the principle of quantisation

Answer 27

The observed charge on an isolated particle is always an integer multiple of e(1,6 x 10^-19)

Question 28

What is Coulomb’s law

Answer 28

Two point charges in free space or air exert forces on each other. The force is directly proportional to the product of the charges and inversely proportional to the square of their distance between the charges

Question 29

What is an electric field

Answer 29

A region of space in which an electric charge experienced a force. The direction of the electric field at a point is the direction that a positive test charge would move if placed at that point

Question 30

Define electric field strength

Answer 30

The force per unit positive charge

Question 31

How can we determine if there is an electric field in a certain area

Answer 31

Place a test charge in the area. If the charge experienced a force, there is an electrical field in the area.

Question 32

Learn the internet electric field lines on page 241

Answer 32

Did you get it right ?

Question 33

What is an electric field line

Answer 33

An imaginary line that indicates the direction and strength along which a positive test charge will move if it is placed at a specific point in the electric field

Question 34

What are the properties of electric field lines

Answer 34

- They originate and end perpendicularly to the surface of the charged object. - They can never cross or touch each other. - they are most dense (closer to each other) where the field is the strongest and are least dense (further from each other) where the field is the weakest. - Their direction is, according to convention, from the positively charged object to the negatively charged object. -They surround the charged object in three dimensions. We only draw a few lines on one plane. -There is a uniform field between two oppositely charged parallel plates (except at the terminal points).

Question 35

How is the electric field between parallel charged plates

Answer 35

There is a uniform electrical field between the two oppositely charged parallel plates. A positive test charge will experience the same electrostatic force at any point in an electrical field between two positively charged parallel plates

Question 36

How is the electric field around point charges and charged spheres

Answer 36

The electric field around point charges and charged spheres are not uniform. The further you move away from the charge or sphere, the weaker the electric field as well as the electrostatic force becomes

Question 37

How is the electrical field around an irregular object

Answer 37

For objects that have an irregular shape the greatest charge is found at the sharpest areas where the electrical field is also the densest.