Electricity Practical Flashcards
(17 cards)
What is the aim of the resistance practical?
To investigate how the length of a wire affects its resistance.
What equipment is needed for the resistance practical?
Power supply, ammeter, voltmeter, crocodile clips, wire (on a ruler), variable resistor.
What is the method for the resistance practical?
. Attach wire to a ruler.
2. Connect circuit with power pack, ammeter, voltmeter.
3. Measure voltage and current for different wire lengths.
4. Use R = \frac{V}{I} to calculate resistance.
5. Repeat and average.
What should be kept constant in the resistance practical?
Same material and thickness of wire.
• Same voltage.
• Room temperature.
What is the expected result?
Resistance increases as wire length increases (directly proportional).
What are common sources of error in this practical?
Heating of the wire.
• Poor connections.
• Inaccurate length measurements.
How can errors be reduced?
Use a low voltage to prevent heating.
• Use digital meters.
• Check connections are tight.
What is the aim of the I–V characteristics practical?
To investigate how current changes with voltage for different components.
What equipment is needed for the I–V characteristics practical?
Power supply
• Ammeter
• Voltmeter
• Resistor, filament lamp, diode
• Variable resistor
• Wires and a switch
What is the method for the I–V characteristics practical?
- Set up circuit with component, ammeter in series, voltmeter in parallel.
- Adjust variable resistor to change voltage.
- Record current and voltage.
- Plot I–V graph.
- Repeat for each componen
What should be kept constant in the I–V practical?
Type of component
• Ambient temperature
• Equipment setup (except the component)
What is the expected I–V graph shape for a resistor?
A straight line through the origin (current ∝ voltage).
What is the expected I–V graph shape for a filament lamp?
A curved line – as current increases, resistance increases (not directly proportional).
What is the expected I–V graph shape for a diode?
Current flows in one direction only – flat line when reverse-biased, curves up when forward-biased.
Why must the diode be placed the correct way round?
Because current only flows through a diode in one direction (forward bias).
What are common errors in the I–V characteristics practical?
• Inconsistent voltmeter readings
• Overheating components
• Poor connections
How can you reduce errors in this practical?
Switch off circuit between readings
• Take multiple readings and average
• Use low voltages
