Electricity

Question 1

current

Answer 1

the measure of the flow of electrons around a circuit. Measured by amperes/ amps (A)

Question 2

Potential difference

Answer 2

Same as voltage.
The fore driving the flow of electrons
Measure by volts (V)

Question 3

Resistance

Answer 3

Anything that resists or slows the flow of electrons.

Measured by ohms

Question 4

The current flowing through a component depends on …

Answer 4

1) The potential difference around the component

2) The resistance across the component

Question 5

Relationship between current and resistance

Answer 5

The greater the resistance across the component, the small the current that flows, for a given potential difference

Question 6

Current in a circuit travels from…

Answer 6

positive to negative

Question 7

charge

Answer 7

a measure of the total current that flowed within a period of time.

More charge passes around the circuit when a larger current flows

Question 8

what is charge measured in

Answer 8

coulombs

Question 9

equation for charge, current and time

Answer 9

charge = current x time

Question 10

the equation for potential difference, current and resistance

Answer 10

potential difference = current x resistance

Question 11

Required practical - length of the wire

Answer 11

1) set up the wire
2) connect the wire with two crocodile clips
3) close the switch, record the current and potential difference
4) open the switch, move the second crocodile clip another 10 cm away
5) close switch and record the current and potential difference
6) repeat this for a number of different lengths od the test wire
7) use measurements to calculate the resistance
8) plot a graph of resistance against wire length

Question 12

Required practical - length of the wire - results

Answer 12

resistance is directly proportional to the length of the wire, so when the length of the wire increases, resistance increases

Question 13

Required practical error

Answer 13

zero error - it is difficult to get the crocodile clip exactly at 0cm and there is some resistance caused by the contact between the crocodile clip and the wire. we cannot reduce this risk so we need to subtract the zero error from all our readings
Heating effect - if the temperature of the wire increases, the resistance increases, to reduce this we can keep the pd low so that the current is low, reducing heating in the wire. And turn the current off in between readings and only turn it on when we are taking readings to reduce the heating of the wire

Question 14

series circuit

Answer 14

one loop, no branches so the current can only flow in one path.
if you remove or disconnect one component, the circuit is broken and they all stop. So only a few things are connected in series circuits.

Question 15

current in series circuit

Answer 15

current is the same

Question 16

parallel circuit

Answer 16

A parallel circuit contains branches, so the current splits

if you remove or disconnect one of the components, it hardly affects the others.

Question 17

current in parallel circuit

Answer 17

current is shared between branches, so the current in the branches adds up to the total current leaving the cell

Question 18

convential current

Answer 18

current that flows from the positive end of the cell to the negative end of the cell

Question 19

what does pd tell us about energy transferred

Answer 19

a pd of 1 volt tells us that 1 joule of energy is transferred for each coulomb of charge that is moving through the circuit

Question 20

electric field

Answer 20

An electric field is a region where charges experience a force

Question 21

relationsip between closeness and the strength of the field

Answer 21

as you decrease the distance between the charged object, the strength of the field increases, so the forces between them gets bigger

Question 22

electric field lines

Answer 22

electric field lines go from positive to negative.

they are always at a right angle to the surface, the closer the lines are, the stronger the field is