Electrostatics And Electromagnetism

Question 1

Definition of electrostatics

Answer 1

Study of static electricity where we try to find out the effect charges at rest have on one another

Question 2

Definition of the law of conservation of charge

Answer 2

The sum of all charges remains constant in an isolated system

Question 3

Definition of Coulomb’s law

Answer 3

The force of attraction or repulsion that two charges at rest exert on each other is directly proportional to the product of the two charges and inversely proportional to the distance between their centres

Question 4

Definition of electric field

Answer 4

A region in space in which an electric charge experiences a force

Question 5

Definition of electric field strength

Answer 5

The electric field strength at a point is the electrostatic force experienced per unit positive charge placed at that point

Electric field strength at any point in space is the force per unit charge experienced by a positive test charge at that point

Question 6

Definition of magnetic flux

Answer 6

The magnitude of the magnetic field lines that pass through an area

Question 7

What kind of electricity is static electricity?

Answer 7

Stationary electricity (no continuous movement of electrical charges)

Question 8

List the two types of charges

Answer 8

• positive charge
• negative charge

Question 9

What makes a charge positive?

Answer 9

A positive charge on an object originates with the removal or shortage of electrons

Question 10

What makes a charge negative?

Answer 10

A negative charge on an object originates with the addition or surplus of electrons

Question 11

What makes a charge neutral?

Answer 11

When the number of electrons is equal to the number of protons

Question 12

List two ways an object may be charged

Answer 12

• friction
• touch

Question 13

Explain how an object can be charged by friction

Answer 13

• a plastic ruler becomes positively charged when it’s rubbed with a dry cloth as the plastic ruler transfers electons to the cloth
• a glass rod becomes negatively charged when rubbed with a dry cloth as the dry cloth transfers electrons to the glass rod

Question 14

Explain how objects can be charged by touch

Answer 14

When a charged object touches an uncharged object, then both objects obtain the same charge if they’re identical

Question 15

Conversion of milli (m)

Answer 15

×10‐³

Question 16

Conversion of micro (ų)

Answer 16

×10‐⁶

Question 17

Conversion of nano (n)

Answer 17

×10‐⁹

Question 18

Coulomb’s formula

Answer 18

F = KQ¹Q²
———-
r²

Question 19

Formula for energy

Answer 19

Energy = field strength
——————–
electron charge

Question 20

Formula for electric field strength

Answer 20

E (NC‐¹) = force on charge q(N)
—————————–
electron charge (C)

Question 21

Formula of electric field strength

Answer 21

E = kQ
—–
r²

Question 22

What three factors determine the magnetic field?

Answer 22

• strength of field
• no. of lines / speed of motion
• no. of turns in the coil

Question 23

Unit of magnetic field (B)

Answer 23

Tesla (T)

Question 24

Unit of phi

Answer 24

Weber (Wb)

Question 25

When does maximum flux occur

Answer 25

When the surface is perpendicular to the field (¤ = 0°)

Question 26

When does minimum flux occur?

Answer 26

When the surface is parallel to the field (¤ = 90°)

Question 27

Faraday’s law

Answer 27

Magnitude of induced EMF is proportional to rate at which magnetic flux changed