Paper 1 - I-V Characteristics

Question 1

what does the term ‘I-V characteristic’ refer to

Answer 1

a graph which shows how the current flowing through a component changes as the pd across it increases

Question 2

what are some components you can test and state whether they’re linear or not
3 points

Answer 2

1) ohmic conductor - linear
2) filament lamp - non-linear
3) diode - non-linear

Question 3

what are linear and non-linear components
2 points

Answer 3

1) linear - has a I-V characteristic that’s a straight line
2) non-linear - have curved I-V characteristic

Question 4

what is the method for investigating I-V characteristics
6 points

Answer 4

1) set up the test circuit
2) begin to vary the variable resistor
3) take several pairs of readings from the ammeter and voltmeter to see how the pd across the component varies as the current changes
4) repeat each reading twice more to get an average pd at each current
5) swap over the wires connected to the battery so the direction of the current is reversed
6) plot a graph of current against voltage for the component

Question 5

draw the test circuit

Answer 5

pg 43

Question 6

draw the I-V characteristic for an ohmic conductor and describe it
2 points

Answer 6

1) pg 43
2) the current through the conductor is directly proportional to pd

Question 7

draw the I-V characteristic for a filament lamp and describe it
3 points

Answer 7

1) pg 43
2) as the current increases the temp of the filament increases, so the resistance increases
3) this means less current can flow per unit pd so the graph gets shallower

Question 8

draw the I-V characteristic for a diode and describe it
3 points

Answer 8

1) pg 43
2) current will only flow through a diode in one direction
3) it has a very high resistance in the reverse direction

Question 9

how can you calculate the resistance from the graphs

Answer 9

using R=V/I, taking the reading of pd and current from one point on the graph