Topic 2 Third Form

Question 1

What is current?

Answer 1

A flow of electrical charge

Question 2

What is current measured in?

Answer 2

Amps (A)

Question 3

What is potential difference

Answer 3

energy transferred per coulomb as it moves between two points in an electric circuit

Question 4

What is potential difference also called?

Answer 4

Voltage

Question 5

What is pd measured in?

Answer 5

Volts (V)

Question 6

What is resistance?

Answer 6

measure of opposition to the flow of electric current in a circuit

Question 7

What is resistance measured in?

Answer 7

Ohms

Question 8

When does current flow in a circuit?

Answer 8

When there is a complete circuit and a source of potential difference

Question 9

What happens to current when resistance INCREASES?

Answer 9

Current decreases

Question 10

What is current the rate of?

Answer 10

Flow of charge of electrons

Question 11

What is the equation linking charge, current and time? Symbols and words

Answer 11

Q= I x t
Charge = current times time

Question 12

How do you calculate current from charge and time?

Answer 12

I = Q÷t
Current equals charged divided by time

Question 13

How do you calculate time from charge and current?

Answer 13

t =Q÷1
Time = charge divided by current

Question 14

How are components arranged in a series circuit

Answer 14

in a single, continuous loop, connected end-to-end so that the current follows only one path

Question 15

What happens if one component is removed in series?

Answer 15

The circuit is broken and the current stops

Question 16

What is current in a series circuit

Answer 16

the same everywhere

Question 17

What happens to potential difference in series

Answer 17

It is shared between components equally

Question 18

What is the total pd in series?

Answer 18

V total= all the components added together (v1 + v2 + v3 = total v)

Question 19

What happens to the TOTAL resistance in series when more components are added?

Answer 19

the total resistance increases as more components are added

Question 20

Total resistance formula in series circuit

Answer 20

R total = r1 + r2 + rn…

Question 21

What happens to current when resistance increases in series

Answer 21

It decreases

Question 22

How does resistance affect the share of potential difference?

Answer 22

A bigger resistance = bigger share of potential difference

Question 23

What happens when cells are connected in series?

Answer 23

Their voltages add up

Question 24

Example: two 1.5 V cells in series. What is the total potential difference

Answer 24

3 V

Question 25

How are components arranged in parallel circuits

Answer 25

On different branches meaning the current can go down different routes

Question 26

What happens if one branch is removed?

Answer 26

The others will still work

Question 27

What happens to the potential difference in parallel circuits?

Answer 27

It is the same across all the components

Question 28

What happens to current in parallel

Answer 28

It splits between branches

Question 29

Total current formula in parallel

Answer 29

I total = I1 +I2 +In…

Question 30

How does resistance DECREASE in parallel

Answer 30

total resistance decreases as more branches are added

Question 31

How does total resistance compare in parallel

Answer 31

is always less than the smallest individual resistor

Question 32

What happens to pd across each resistor in parallel compared to the source

Answer 32

It stays the same as the source

Question 33

What happens to the total CURRENT when adding a resistor in parallel

Answer 33

increases the total current flowing from the source

Question 34

what happens to the total RESISTANCE when adding a resistor in parallel?

Answer 34

decreases the total resistance of a circuit

Question 35

What is the LAW linking voltage, current and resistance?

Answer 35

Ohm’s law

Question 36

What is the equation linking voltage, current and resistance? Symbols and words

Answer 36

V = I x R Voltage = current times resistance

Question 37

How do you calculate current using Ohm’s law

Answer 37

I = V divided by R Current = voltage divided by resistance

Question 38

How do you calculate resistance using Ohm’s law?

Answer 38

R = V divided by I

Question 39

What does a voltmeter measure

Answer 39

Potential difference

Question 40

How is a voltmeter connected?

Answer 40

across the component being measured (over the top)

Question 41

What does an ammeter measure?

Answer 41

Current

Question 42

How is an ammeter connected?

Answer 42

must be connected in series with the circuit component whose current is being measured so not across just in the circuit

Question 43

What is an ohmic conductor?

Answer 43

A conductor with constant resistance meaning the current flowing through it is directly proportional to the voltage applied across it

Question 44

What is the relationship between current and voltage in an ohmic conductor?

Answer 44

They are directly proportional to

Question 45

What happens to resistance as temperature increases In a filament lamp?

Answer 45

Resistance increases

Question 46

What shape is the I-V graph for a filament lamp?

Answer 46

Curved

Question 47

What direction does current flow in a diode

Answer 47

One direction only = from positive to negative

Question 48

What happens if current is reversed in a diode?

Answer 48

causes it to stop conducting, behaving like an open switch that blocks electricity

Question 49

What shape is the I-V graph for a diode?

Answer 49

It is flat then suddenly inclines in a steep ark

Question 50

What is needed for current to flow

Answer 50

A complete (closed) circuit and a source of potential difference

Question 51

What provides the ‘push’ in a circuit?

Answer 51

Potential difference

Question 52

In a SINGLE closed loop , what is true about current ?

Answer 52

It has the same value everywhere

Question 53

Why is adding components into a series not always good?

Answer 53

If one breaks the entire circuit stops

Question 54

What must happen for a current at a junction ?

Answer 54

Total current in = total current out

Question 55

Why does adding resistance reduce current in series?

Answer 55

Because total resistance increases

Question 56

Why does adding a branch increase current in parallel circuits?

Answer 56

Because current has more paths to flow

Question 57

What are components with curved I-V graphs called?

Answer 57

Non-linear components

Question 58

Why does a filament lamp’s resistance increase?

Answer 58

Because it heats up

Question 59

What does resistance do compared to current?

Answer 59

Opposes the flow of current

Question 60

What does potential difference do to charge in a circuit?

Answer 60

Pushes charge around the circuit

Question 61

How to know if a graph obeys Ohms law?

Answer 61

straight line passing through the origin (0,0)