Required Practical 4: Current / PD Characteristics.

Question 1

What is the purpose for the practical?

Answer 1

• ## Investigate the current/potential difference characteristics of circuit components.

Question 2

How should the circuit be set up?

Answer 2

• Battery connected by wires to a resistor.
• Resitor is in series with an ammeter and variable resistor.
• Voltmeter in parallel across the resistor.

Question 3

What is the method for the practical? (resistor).

Answer 3

1) Use voltmeter to read the potential difference across the resistor + use Ammeter to read the current across the resistor + record values on table.
2) Adjust the variable resistor, record the new readings on voltmeter and ammeter + do several times for a range of results.
3

Question 4

What is the method for this practical? (Switch direction of battery).

Answer 4

1) Switch direction of battery.
2) Direction of potential difference is reversed + Both voltmeter and ammeter should have negative values.
3) Take several readings of potential difference and the current.

USING BOTH RESULTS YOU PLOT A GRAPH WITH CURRENT AND POTENTIAL DIFFERENCE.

Question 5

What does the graph look like? (Switched direction of battery and resistor)?

Answer 5

• Current through the resistor and potential difference is directly proportional.
• Ohmic conductor.
• Changing direction of PD there is still a straight line.

Question 6

When do we only see this graph?

Answer 6

• Temperature is constant.
• Resistor gets hot= graph will not have this shape.
• Don’t leave the circuit connect long as temperature increases?

Question 7

What is the method for this practical? (Fillament lamp)

Answer 7

1) Adjust the variable resistor and read the potential difference and current..
2) Range of values with batteries forward and reverse.

Question 8

What does fillament graph look like?

Answer 8

1) Current is not proportional to the potential difference/
- Current increases = temperature of lamp increases.
- Increased resistance.
- Same shape if we change the direction of potential difference.

Question 9

What does the method? (diode).

Answer 9

• NOTE TO HAVE EXTRA RESISTOR (diodes are easily damaged by a high current).
• Milliammeter (Current will be slow).

1) Adjust the variable resistor and record the current and the potential difference over a range of results with forward and backwards directio.

Question 10

What is the graph? (Diode).

Answer 10

• Get a current when potential difference is around 0.6-0. volts.
• Beyond as PD increases the current increases.
• no current if PD is reveresed.
• Reversed direction diode has high resistance.