P2.3 Electricity

Question 1

What is meant by the term electricity?

Answer 1

The flow of negatively charged electrons around a circuit

Question 2

What do conductors have to make them work?

Answer 2

Free electrons

Question 3

How do insulators work?

Answer 3

They do not have free electrons

Question 4

How does current flow?

Answer 4

From the negative terminal to the positive terminal

Question 5

What unit is charge in?

Answer 5

Couloms

Question 6

What unit is current (i) in?

Answer 6

Amps

Question 7

What unit is time in?

Answer 7

Seconds

Question 8

What is the formula for total charge?

Answer 8

Charge= current x time

Question 9

What is meant by voltage?

Answer 9

The force of the electrons flowing around the current which comes from the batteries and is used up in all components

Question 10

When will voltage only be provided to a circuit?

Answer 10

If one side has a negative terminal and the other side has a positive terminal

Question 11

What is meant by the total voltage in the circuit? (Def)

Answer 11

The sum of the batteries that are connected the right way minus the batteries that are connected the wrong way

Question 12

What is an ammeter used to measure and how is it connected?

Answer 12

Used to measure current and is connected in series

Question 13

What happens to the current when it is in series?

Answer 13

It is the same at all points

Question 14

What happens to the current when it is in parallel?

Answer 14

Current is divided amongst all branches

Question 15

What does a voltmeter measure and how is it connected?

Answer 15

Measures voltage
Connected in parallel

Question 16

What is meant by resistance?

Answer 16

The opposition to the flow of a current through a wire or component

Question 17

What is the formula for voltage?

Answer 17

Voltage=current x resistance

Question 18

What unit is voltage gave in?

Answer 18

Volts

Question 19

What unit is resistance gave in?

Answer 19

Ohms

Question 20

What are the 4 factors that affect resistance?

Answer 20

Length
Cross sectional area
Material
Temperature

Question 21

What does Ohms Law state?

Answer 21

At a constant temperature the current through a conductor is directly proportional to the voltage across it

Question 22

In a graph showing the current in a filament bulb, why will the graph NOT be directly proportional to the voltage applied?

Answer 22

The temperature is increasing inside of the filament bulb

Question 23

In a series circuit, what is the Rtotal?

Answer 23

Rtotal = R1+R2….

Question 24

In a parallels circuit what is the Rtotal?

Answer 24

Rtotal= R1 x R2/ R1+R2

Question 25

What causes Joule heating?

Answer 25

Electrons collide with atoms as they pass through a conductor, the light electrons loose energy whilst the heavy electrons gain energy which leads to an increase in vibration

Question 26

What is the formula for energy transferred?

Answer 26

energy transferred = voltage × charge or energy transferred = voltage × current × time

Question 27

What unit is energy in?

Answer 27

Joules

Question 28

What is the formula for (electrical) power?

Answer 28

electrical power = voltage × current

Question 29

What unit is power in?

Answer 29

Watts

Question 30

What does Joules law state?

Answer 30

Joule’s law states that the power generated in an electrical component is the product of the current in the component and the voltage across it

Question 31

What is the formula for the number of units used?

Answer 31

number of units used = power rating (in kilowatts) × time (in hours)

Question 32

What is the formula for the total cost?

Answer 32

total cost = number of units used × cost per unit

Question 33

How does a one way switch work?

Answer 33

When the switch is open there is air between the conducting contacts and because air is an insulator, no current flows

Question 34

What wire has blue insulation?

Answer 34

Neutral wire

Question 35

What hand of the pin should the neutral wire be connected to?

Answer 35

The left hand of the pin

Question 36

What wire has brown insulation?

Answer 36

The live wire

Question 37

What hand of the pin should the neutral wire be connected to?

Answer 37

The right hand of the pin

Question 38

What wire has striped yellow and green insulation?

Answer 38

The earth wire

Question 39

What hand of the pin should the earth wire be connected to?

Answer 39

The top hand of the pin

Question 40

What is the neutral wire?

Answer 40

The wire in the mains voltage system that is permanently 0 volts

Question 41

What is the live wire?

Answer 41

The dangerous wire in the mains voltage system in which the voltage is changing

Question 42

What is the earth wire?

Answer 42

The wire that connects the metal frame of the appliance to the earth

Question 43

What is a fuse?

Answer 43

A short wire which melts to disconnect a circuit when too much current flows through it

Question 44

What is the purpose of a fuse? (e.g whom or what does it protect?)

Answer 44

To protect the appliance itself

Question 44

What is the purpose of an earth wire?

Answer 44

To prevent harm falling onto the user

Question 45

Define the term "double insulation"

Answer 45

A safety technique where the electrical appliance is encased in an insulating plastic to prevent the user coming into contact with a live wire and being harmed

Question 46

What is cell polarity?

Answer 46

Cell polarity is concerned with which end of a cell is positive and which end is negative

Question 47

In a parallel circuit with 3 sets of resistors, what is the formula for Rtotal?

Answer 47

1/Rt= 1/R1 + 1/R2 + 1/R3…