Electricity: Resistance Required Practical

Question 1

What equipment is used to investigate the affect of the length of wire on resistance?

Answer 1

• dc power supply
• voltmeter
• ammeter
• length of wire mounted on a metre rule
• crocodile clips
• connecting leads

Question 2

What is the independent variable in the resistance required practical?

Answer 2

length of wire

Question 3

What is the dependent variable in the resistance required practical?

Answer 3

Voltage/ potential difference
Current

Question 4

What safety risk is there in doing the resistance required practical? How can this be reduced?

Answer 4

Wire may get hot.
Switch off between readings.

Question 5

How would you use your results to calculate the resistance?

Answer 5

Rearrange the formula V = IR for resistance.
R = V/I

Question 6

How does the length of wire affect resistance?

Answer 6

longer wire = increased resistance

Question 7

Is the length of wire directly proportional to the resistance? How is this shown on a graph?

Answer 7

Yes.

The graph gives a straight line through the origin.

Question 8

What are some control variables in the resistance required practical?

Answer 8

• thickness of wire
• material of wire
• temperature of wire (hotter = more resistance bc more movement of ions)