Current, Potential difference and resistance (1)

Question 1

What is meant by direct current?

Answer 1

Current that is always in the same direction

Question 2

Which one of these diagrams X, Y or Z shows the trace that would be seen on the oscillope?
Give a reason for your answer

Answer 2

Y
Only one that shows a direct current

Question 3

What pattern links the amount of charge passing through the heating element and the time the kettle is switched on?

Answer 3

The charge is directly proportional to the time switched on for

Question 4

The reading on ammeter A2 will be ___________the reading on ammeter A1

Answer 4

equal to

Question 5

Which variable did the student keep the same?

Answer 5

Potential difference of the power supply

Question 6

What conclusion should the student make from the bar chart?

Answer 6

As the number of resistors increase, the current decreases

Question 7

Describe how the student could use her circuit to investigate how the current through a filament lamp affects its resistance

Answer 7

• ammeter is used to measure current. voltmeter is used to measure potential difference. the resistance of variable resistor altered to change current in circuit. resistance of filament lamp calculated.

Question 8

Describe how a student would use the circuit to take the readings necessary to determine the resistance of resistor R

Answer 8

• switch on
• read both ammeter and voltmeter
• adjust the variable resistor to change the current
• take further readings
• draw graph of V against I

Question 9

Explain why the student should open the switch after each reading

Answer 9

Resistor would get hot if current left on so its resistance would increase

Question 10

Describe the action of the fuse in a circuit

Answer 10

If the current is above 5A, fuse melts breaking the circuit