Electricity, P2

Question 1

How must an ammeter be placed in a circuit

Answer 1

In series

Question 2

How must a voltmeter be placed in a circuit

Answer 2

In parallel

Question 3

charge flow formula

Answer 3

Current × time 𝑄 = 𝐼 𝑡

Question 4

potential difference formula

Answer 4

current × resistance 𝑉 = 𝐼 𝑅

Question 5

total resistance formula =

Answer 5

resistance of component 1 +
resistance of component 2
𝑅𝑇
= 𝑅1 + 𝑅2

Question 6

The 2 different formulas for power is

Answer 6

power = current × potential difference 𝑃 = 𝐼 𝑉
power = (current)2 × resistance 𝑃 = 𝐼2𝑅

Question 7

What are the 2 formulas for energy transferred

Answer 7

energy transferred = power × time 𝐸 = 𝑃𝑡
energy transferred = charge flow × potential difference 𝐸 = 𝑄𝑉

Question 8

How does energy transfer round a circuit?

Answer 8

Electrons are supplied with energy by a cell/battery or mains electricity, which then move through the wires to transfer energy

Question 9

Does charge/current always flow from negative(-) to positive(+) or positive(+) to negative(-)?

Answer 9

Positive to negative. + to -

Question 10

What are coulombs?

Answer 10

A large group of electrons in a circuit

Question 11

What do coulombs (C) measure?

Answer 11

Charge (Q)

Question 12

What is potential difference (p.d) measured in?

Answer 12

Volts

Question 13

What is p.d the measure of?

Answer 13

How much energy is transferred to/by each coulomb of electrons/charge

Question 14

What is current (I)?

Answer 14

The flow of charge

Question 15

How do we measure current?

Answer 15

Using an ammeter, in Amps (A)

Question 16

What is OHMS law?

Answer 16

V = I x R
Potential difference = Current x Resistance

Question 17

When using a fixed resistor, are V (p.d) and I (current) directly proportional or indirectly proportional?

Answer 17

Directly proportional

Question 18

Is resistance in a filament lamp constant or not constant

Answer 18

NOT constant

Question 19

When using a filament lamp, does a larger current in the circuit equal a higher or lower resistance across the filament lamp?

Answer 19

Higher

Question 20

What does LED stand for?

Answer 20

Light Emitting Diode

Question 21

Do diodes allow flow of current in multiple directions?

Answer 21

No, one direction only (Low resistance in forward direction, high resistance in reverse direction)

Question 22

In series circuits…

Answer 22

-Total p.d is shared between all components
-Current is the same for all components
-Total resistance = sum of resistances

Question 23

In parallel circuits…

Answer 23

-p.d for each branch = total p.d of cell/battery
-Current is split between branches
-Adding more resistors decreases resistance

Question 24

What colour is the neutral wire?

Answer 24

Blue

Question 25

What colour is the live wire?

Answer 25

Brown

Question 26

What colour is the earth wire?

Answer 26

Green and yellow

Question 27

Role of earth wire

Answer 27

It is a safety feature: acts as an escape route for current that would otherwise cause an electric shock if appliance is touched

Question 28

What is the UK mains voltage?

Answer 28

230V

Question 29

What is a direct potential difference (p.d.)

Answer 29

A potential difference that only acts in one direction

Question 30

What are the 3 types of fuse?

Answer 30

3A fuse, 5A fuse, 13A fuse

Question 31

Every plug has a fuse connected to the live wire. What is a fuse?

Answer 31

A thin metal wire in a tube that is designed to melt or ‘blow’ if there is a fault that causes a high currents

Question 32

What is the role of the national grid?

Answer 32

To distribute electricity to where it is needed?

Question 33

What 5 components are in the national grid? Order them in terms of when they receive the electricity (first to last)

Answer 33

Power station—>Step up transformer—>National grid cables—>Step down transformer—>Homes

Question 34

Why doesn’t current from power stations go straight to houses?

Answer 34

They produce a high current, so lots would be lost as heat due to the resistance of the cables

Question 35

Role of a step up transformer

Answer 35

Increases the voltage to 123KV, which decreases the current reducing the power lost to heat in the cable

Question 36

Role of a step down transformer

Answer 36

Reduces voltage down to a safer and usable 230V for for homes and businesses

Question 37

What is the frequency of the mains supply? (Hz)

Answer 37

50Hz

Question 38

What is static electricity?

Answer 38

When electrons are transferred between to insulating materials, they will remain charged

Question 39

What happens if an object gains electrons?

Answer 39

It becomes negatively charged

Question 40

What happens if an object loses electrons?

Answer 40

It becomes positively charged

Question 41

Opposite charges …

Answer 41

Attract

Question 42

Like charges …

Answer 42

Repel

Question 43

What happens when you touch a Van Der Graaf generator?

Answer 43

Every part of you becomes positively charged because it takes away electrons, that’s why your hairs stand up - they are repelled from your head

Question 44

What is an electric field?

Answer 44

A region around a charged object where other charges objects experience a force

Question 45

What is an electric field?

Answer 45

A region around a charged object where other objects experience a force