required practical - resistance

Question 1

what is resistance, high resistance, low resistance?

Answer 1

Resistance is opposition to the flow of current.
A high resistance means it is harder for current to flow through.
A low resistance means current will flow through more easily.

Question 2

what is the equation for working out resistance

Answer 2

resistance = potential difference / current
or
R=v/I

Question 3

what does a voltmeter measure

Answer 3

measures the potential difference across the wire

Question 4

what does an ammeter measure

Answer 4

measures the current in the circuit

Question 5

explain the method used to see how resistance depends on the wire

Answer 5

1. connect the wire to a meter ruler using tape and then connect the wire to the rest of the circuit using crocodile clips
   - this means that only the part of the wire between clips is actually connected to the circuit. to increase the length of the wire move the clips apart
2. record the amount of current and potential difference for each length of the wire you are measuring and plot a graph once resistance has been calculated

Question 6

what type of graph should resistance and length of the wire be

Answer 6

directly proportional

Question 7

what are the two errors in the experiment

Answer 7

1. zero error
2. heating effect

Question 8

explain how the zero effect, effects the results

Answer 8

the zero effect is an error on a measuring instrument when a value should be zero. for example, crocodile clip isn’t exactly on zero
also, some resistance is created by the contact between the clip and wire

Question 9

explain the heating effect and how this can be reduced

Answer 9

if the temperature of the wire increases then the resistance also will.

reducing - use a lower potential difference and only turn on the current when taking a reading