Topic 2 Core question - Electricity

Question 1

State the rule for current in a series circuit

Answer 1

the current is the same at every point in the circuit and in every component

Question 2

State the rule for the potential difference in a series circuit

Answer 2

the total potential difference of the power supply is shared between components

Question 3

State the rule for resistance in a series circuit

Answer 3

the more resistors, the greater the resistance. RT=R1+R2

Question 4

State the rule for current in a parallel circuit

Answer 4

the total current through the whole circuit is split between the different branches

Question 5

State the rule for the potential difference in a parallel circuit

Answer 5

the potential difference across each branch in the circuit is the same

Question 6

State the rule for resistance in a parallel circuit

Answer 6

adding more resistors in parallel decreases resistance

Question 7

What colour is the live wire in a three core cable?

Answer 7

brown

Question 8

What colour is the neutral wire in a three core cable?

Answer 8

blue

Question 9

What colour is the earth wire in a three core cable?

Answer 9

green and yellow

Question 10

The potential difference between the live wire and others in the plug is _____ V

Answer 10

230V

Question 11

Current flows into an appliance through the _______ wire

Answer 11

live

Question 12

Current flows out of an appliance through the ______ wire

Answer 12

neutral

Question 13

The _________ wire is a safety feature of appliances

Answer 13

earth

Question 14

Potential difference between the neutral wires and others in the plug should be ____ V

Answer 14

0 Volts

Question 15

Electric Current is….?

Answer 15

the flow of electric charge

Question 16

Potential difference between two points in a circuit is….?

Answer 16

the work done when a coulomb of charge passes between the points.

Question 17

In a circuit the potential difference causes …..?

Answer 17

charge to flow

Question 18

Resistance is…?

Answer 18

caused by anything which opposes the flow of electric charge

Question 19

Particles which can be ‘charges’ in electric circuits are…

Answer 19

electrons or ions

Question 20

What is a series circuit?

Answer 20

A circuit with only one route for charge to flow

Question 21

What is a parallel circuit?

Answer 21

A circuit with more than one route for charge to flow

Question 22

State the equation for charge flow

Answer 22

Charge flow(C) = Current(A) x Time(s)
Q=It

Question 23

State the equation for potential difference

Answer 23

Potential Difference(V) = Current(A) x Resistance(Ω)
V=IR

Question 24

State the equation for power

with current and potential difference

Answer 24

Power(W) = Current(A) x Potential difference(V)

P=IV

Question 25

State the equation for power | with current and resistance

Answer 25

Power(W) = Current²(A) x Resistance(Ω) | P=I ²R

Question 26

State the equation for energy transferred | with power and time

Answer 26

``` Energy transferred(J) = Power(W) x Time(s) E=Pt ```

Question 27

State the equation for energy transferred | with charge flow and potential difference

Answer 27

``` Energy transferred(J) = Charge flow(C) x Potential difference(V) E=QV ```

Question 28

Describe the I-V characteristic for a fixed resistor

Answer 28

Current and potential difference is directly proportional, resistance is constant

Question 29

Describe the I-V characteristic of a filament lamp

Answer 29

Resistance is not constant, it increases as p.d. increases

Question 30

Explain why resistance increases with increased p.d. in a filament lamp

Answer 30

temperature increases causing ions to vibrate and increasing collisions with electrons flowing through the filament

Question 31

Describe the I-V characteristic of a diode

Answer 31

The current only flows through the diode in one direction, there is a very high resistance in the reverse direction.

Question 32

Current which regularly changes direction is called…

Answer 32

alternating current

Question 33

An example of alternating current is…?

Answer 33

mains electricity

Question 34

Current which flows in one direction is…?

Answer 34

direct current

Question 35

An example of direct current is…

Answer 35

batteries

Question 36

What is the potential difference of mains electricity in the UK?

Answer 36

230V

Question 37

What is the frequency of the alternating current in UK mains electricity?

Answer 37

50Hz

Question 38

The national grid consists of…?

Answer 38

Cables and transformers

Question 39

Are power stations part of the national grid?

Answer 39

no

Question 40

What does a step up transformer do?

Answer 40

Increases p.d.

Question 41

What does a step down transformer do?

Answer 41

reduces p.d. to 230 V

Question 42

Why are transformers used?

Answer 42

reduce current so that less heat is lost in cables, increases efficiency