Electrical Fundementals

Question 1

What do all materials contain?

Answer 1

All materials contain both positive and negative charges, usually distributed evenly.

Question 2

What is static electricity?

Answer 2

Positive and negative charges are unevenly distributed.

Question 3

How can static electricity be generated?

Answer 3

Contact friction, or induction.

Question 4

What happens when you rub a glass rod with fur?

Answer 4

The rod becomes negatively charged.

Question 5

What happens when you rub a glass rob with silk?

Answer 5

The rod becomes positively charged.

Question 6

What occurs when two materials are rubbed together?

Answer 6

Electrons move from one material to the other. (Static electricity)

Question 7

How can a charged glass rod charge other objects?

Answer 7

Touching it to an uncharged object, a metallic bar.

Question 8

What happens when a positively charged rod is brought near an uncharted metal bar?

Answer 8

It draws the bars electrons towards the rod, redistributing the charges within the bar.

Question 9

What charge does one end of the metal bar have after being near a positively charged rod?

Answer 9

One end of the bar becomes positively , while the other end in negatively charged.

Question 10

What do opposite charges do?

Answer 10

Attract to each other.

Question 11

What do like charges do?

Answer 11

Repel.

Question 12

What is a pith ball?

Answer 12

A lightweight ball, coated with a conductive material.

Question 13

What does Coulomb’s law describe?

Answer 13

The force between two electrically charged bodies.

Question 14

What does Coulomb’s law state?

Answer 14

The electrostatic force between two-point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.

Question 15

How does charge magnitude affect the electrostatic force?

Answer 15

The force increases with the product of the magnitudes of the charges.

Question 16

What does coulobms law calculate?

Answer 16

Force of attraction

Question 17

Typical value of K?

Answer 17

9.0x10^9Nm^2/C^2

Question 18

SI units for: force, charge, distance

Answer 18

Newton, coulombs, meters

Question 19

How is conductivity classified among materials?

Answer 19

Materials with very low conductivity are classified as insulators.

Question 20

What occurs when an electron enters a conductor?

Answer 20

electric current.

Question 21

What is electric current?

Answer 21

The movement of electrons through a conductor.

Question 22

What occurs when a conductor narrows, like in a light bulb filament?

Answer 22

Electrons move faster to maintain the same current leading to greater heating in a narrower section.

Question 23

Is chemically pure water a good conductor of electricity?

Answer 23

No

Question 24

What does tap water contain that effects ins conductivity?

Answer 24

Water molecules along with substances

Question 25

What type of current is used to generate gases during electrolysis of water?

Answer 25

Direct current (DC)

Question 26

What is the conducting substance is electrolysis called?

Answer 26

An electrolyte

Question 27

What carries charge when an electric current flows through an electrolyte?

Answer 27

Inos

Question 28

What are positive and negative ions called, and which direction do they flow?

Answer 28

Positive: cations, cathode Negative: anions, anode

Question 29

What is often emitted during gas discharge?

Answer 29

Visible light

Question 30

What happens during collisions between high speed electrons and gas atoms?

Answer 30

Ionise the atoms producing more free electrons.

Question 31

What is the process of creating large numbers of free electron and positive ions called?

Answer 31

Electron cascade.

Question 32

What is a vacuum

Answer 32

No particles

Question 33

What is voltage a measure of?

Answer 33

PD in electrical charge between two points.

Question 34

What is electric current?

Answer 34

The rate of flow of electrical charge in a certain direction.

Question 35

Unit of electric charge?

Answer 35

Ampere (A) amp

Question 36

How is current defined?

Answer 36

The number of coulombs of charge flowing through the cross-section of a conductor I one second.

Question 37

What is the symbol for electrical charge?

Answer 37

Q, measured in coulombs (C)

Question 38

What is conventional current flow?

Answer 38

Direction of positive charge flow

Question 39

How is potential difference measured?

Answer 39

Volts, between two points of a circuit.

Question 40

Equation for current?

Answer 40

I=Q/t

Question 41

Equation for resistance?

Answer 41

R=V/I

Question 42

What is doping in their context of semiconductors?

Answer 42

The process of adding impurities to create semiconductors that produce more electrons (n-type) or more holes (p-type)

Question 43

What is a photovoltaic cell?

Answer 43

A solar see that ruins light into electrical energy.

Question 44

How is a photovoltaic cell structured?

Answer 44

Thin slice of n-type silicon placed over a thicker slice of p-type silicon.

Question 45

What happens at the p-n junction of a photovoltaic cell?

Answer 45

When light falls on the p-n junction both electrons and hole flow across it generation an electromotive force (EMF)

Question 46

What type of energy do thermoelectric generators utilise?

Answer 46

Thermal energy.

Question 47

What happens when you rub an insulator?

Answer 47

Electrical charges separate, generating an EMF.

Question 48

What are some hazards associated with static electricity?

Answer 48

Spark or shock

Question 49

Where does sparking typically occur in an electric field?

Answer 49

At points and corners.

Question 50

What is the piezoelectric effect?

Answer 50

Generation of voltage when pressure is applied to deform a piezo crystal.

Question 51

How are charges collected in a piezoelectric all crystal?

Answer 51

Using m,arterial; like aluminium foil to form terminals.

Question 52

Wheat are some applications of the piezoelectrical effect?

Answer 52

Record players, microphones, loudspeakers, lighters

Question 53

How is voltage generated in terms of charge?

Answer 53

Voltage is generated by the separation of charge creating a potential difference between two points.

Question 54

What are voltage generators based on chemical principles called?

Answer 54

Galvanic cells

Question 55

Multiply galvanic cells?

Answer 55

Battery

Question 56

Fletcher

Answer 56

Fletcher

Question 57

What are the two main components of most electrical generators?

Answer 57

Static ring called ‘stator’, and a rotating set of coils on an axle known as the ‘rotor’

Question 58

What type of voltage do most electrical generators provide?

Answer 58

Alternators

Question 59

What is the phenomenon called when a conductor moves through a magnetic field and an EMF is induced?

Answer 59

Generator effect

Question 60

What results from the deflection of electrons in a conductor moving through a magnetic field?

Answer 60

Electrical voltage.

Question 61

What type of energy is converted into electrical energy in the generator effect?

Answer 61

Kinetic energy

Question 62

How can the efficiency of EMF be improved in electromagnetic induction?

Answer 62

Coil of wire instead of a single conductor.

Question 63

Applications of electromagnetic induction?

Answer 63

Field telephones

Question 64

Can primary cells supply voltage without charging?

Answer 64

Yes

Question 65

What determines the capacity of galvanic cells?

Answer 65

Construction and size

Question 66

What is one disadvantage of zinc-carbon batteries?

Answer 66

Oxidises and leaks.

Question 67

Alkaline batteries compare to zinc batteries in terms of energy?

Answer 67

Alkaline batteries can deliver up to 5 times more energy.

Question 68

What can alkaline batteries leak?

Answer 68

Potassium hydroxide, so should be removed from devices if not being used from a long time.

Question 69

What is a secondary cell battery?

Answer 69

Rechargeable battery

Question 70

What is the voltage of a lead acid cell when charged and when discharged?

Answer 70

2.2V charged, and 1.83V discharged

Question 71

What is the voltage of a nickel-cadmium cell when fully charged and when discharged?

Answer 71

1.2V charged, and 1V discharged

Question 72

How are cells connected in series?

Answer 72

Unlike terminals

Question 73

Total voltage in series?

Answer 73

Sum of the voltages

Question 74

What happens to the current in a series circuit?

Answer 74

Constant

Question 75

Main advantages of series?

Answer 75

Increases the total voltage

Question 76

How are cells connected in parallel?

Answer 76

Like terminals

Question 77

What happens to the voltage when cells are connected in parallel?

Answer 77

The same

Question 78

What happens to the internal resistance in parallel?

Answer 78

Decreases

Question 79

What is the effect of parallel connections on the current?

Answer 79

Larger current

Question 80

What is source voltage

Answer 80

Total voltage generated by a power source

Question 81

What causes internal resistance in power sources?

Answer 81

Electrolyte and plates

Question 82

How does load current affect terminal voltage?

Answer 82

Load current increases, terminals voltage falls

Question 83

How does LDR control the LED in a circuit?

Answer 83

LDR’s resistance increases therefore switching on the transistor and activating the LED