GCSE Physics Required Practical: Investigating Electrical Components
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Contents
Key Stage 4
Meaning
Investigate the I-V characteristics of electrical components.
Experiment 1a: Resistor
Variables
- Independent Variable: The potential difference across the resistor.
- Dependent Variable: The current through the resistor
Method
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Improving Precision
- Use an ammeter with a greater resolution.
- Use a voltmeter with a greater resolution.
Results
Conclusion
Description
The IV Graph for a resistor shows that:
- As potential difference increases, increases.
- The relationship between potential difference and current is linear (the gradient is constant).
- The current is directly proportional to potential difference.
Explanation
- Resistors obey Ohm's Law so the "current through a resistor at constant temperature is directly proportional to the potential difference across the resistor."
Experiment 1b: Filament Bulb
Variables
- Independent Variable: The potential difference across the bulb.
- Dependent Variable: The current through the bulb
Method
|
Improving Precision
- Use an ammeter with a greater resolution.
- Use a voltmeter with a greater resolution.
Results
Conclusion
Description
The IV Graph for a bulb shows that:
- As potential difference increases, increases.
- At small potential differences] the the relationship between potential difference and current is linear (the gradient is constant).
- At large potential differences the gradient becomes more shallow as the resistance of the bulb increases.
Explanation
- At small potential differences there is a small current so the heating effect of the current is small and the filament remains at a low temperature.
- At large potential differences there is a large electrical current so the heating effect of the current is large which causes the filament to be a high temperature.
- Wires (like the filament) have a greater resistance at higher temperatures, causing the increase in current to be reduced.
Experiment 1c: Diode or LED
Variables
- Independent Variable: The potential difference across the diode.
- Dependent Variable: The current through the diode
Method
|
Improving Precision
- Use an ammeter with a greater resolution.
- Use a voltmeter with a greater resolution.
Results
Conclusion
Description
The IV Graph for a diode shows that:
- For a positive potential difference the current increases rapidly with an increase in potential difference
- For a negative potential difference the current remains negligible and does not increase as the potential difference becomes larger.
Explanation
- The resistance of a diode is very low for current in the forward direction and very high in the back direction.
Experiment 1d: 'NTC' Thermistor
Variables
- Independent Variable: The potential difference across the thermistor.
- Dependent Variable: The current through the thermistor
Method
|
Improving Precision
- Use an ammeter with a greater resolution.
- Use a voltmeter with a greater resolution.
Results
Conclusion
Description
The IV Graph for an 'NTC' thermistor shows that:
- At a high temperature the current increases rapidly with the potential difference
- At a low temperature the current increases slowly with the potential difference.
Explanation
- The resistance of an 'NTC' thermistor increases as the temperature decreases.
Experiment 1a: Resistor
Variables
- Independent Variable: The potential difference across the light dependent resistor.
- Dependent Variable: The current through the light dependent resistor
Method
|
Improving Precision
- Use an ammeter with a greater resolution.
- Use a voltmeter with a greater resolution.
Results
Conclusion
Description
The IV Graph for a light dependent resistor shows that:
- At a high light intensity the current increases rapidly with the potential difference
- At a low light intensity the current increases slowly with the potential difference.
Explanation
- The resistance of an LDR increases as the light intensity decreases.