Current, Potential Difference and Resistance (2)

Question 1

State what happens to the total resistance of the circuit and the current through the circuit when switch S is closed

Answer 1

The total resistance decreases so current increases

Question 2

Name the component in the circuit used to change the potential difference across the resistor

Answer 2

Variable resistor

Question 3

Why has the student plotted points for a line graph and not drawn a bar chart?

Answer 3

The data is continuous

Question 4

What is the most likely point for this anomalous point?

Answer 4

Misreading ammeter

Question 5

Does the data the student obtained support the hypothesis?

Answer 5

Yes as it supports his prediction

Question 6

Describe an investigation a student could do to find how the resistance of a metal sample varies with temperature

Answer 6

• read V and I
• read temperature
• apply heat
• read V and I and at least one other temperature
• determine R from V I
• range of temperature above 50 degrees

Question 7

Which metal sample, P, Q, R, or S, has the data shown in the graph?

Answer 7

Q

Question 8

Suggest a reason for this anomalous result

Answer 8

Thermometer misread

Question 9

Suggest two disadvantages of using this equipment as a thermometer compared to a liquid - in - glass thermometer

Answer 9

• not portable
• needs an electrical supply

Question 10

How can the current through the material be changed?

Answer 10

Adjust the variable resistor

Question 11

What is the relationship between the resistance and the thickness of the conducting putty?

Answer 11

The thicker the putty, the lower the resistance

Question 12

Name one error that may have reduced the accuracy of the results

Answer 12

Measuring length incorrectly

Question 13

Why is component labelled ‘J’ included in the circuit?

Answer 13

To obtain a range of p.d values

Question 14

The resistance of the bulb increases as the potential difference across the bulb increases. Why?

Answer 14

Temperature of the bulb increases