Required practical 3 - Resistance

Question 1

Outcome of practical

Answer 1

Find out how resistance depends on length of wire

Question 2

Steps

Answer 2

1. Set up a series circuit with a voltmeter and ammeter.
2. Attach a wire to a metre ruler using tape
3. Connect the wire to the rest of the circuit using crocodile clips
4. Measure the current and p.d and work out resistance using V=IR
   4.By using the crocodile clips, you can change the length of the wire
5. Repeat step 3 with different lengths of the wire

Question 3

What graph should you get from this experiment

Answer 3

Resistance is directly proportional to length of wire

Question 4

what is a zero error

Answer 4

a reading on the measurement when the value should be zero

Question 5

what type of error is zero error

Answer 5

a systematic error, meaning we cannot reduce it by carrying out repeats

Question 6

how do we go around a zero error in this experiment

Answer 6

subtract the zero error from all the readings

Question 7

why do zero errors occur in this particular experiment

Answer 7

• its hard to get the crocodile clip at exactly zero
• there’s some resistance caused by the contact between the crocodile clip and the wire

Question 8

how does heating effects affect results of this practical

Answer 8

if the temperature of the wire increases, resistance will also increase, affecting results

Question 9

how to reduce heating effects

Answer 9

• use a low p.d to keep current low, reducing any heat in the wire
• only keep the current on whilst taking readings, turn it off between readings