Investigating Resistance
This practical lesson covers:
- How to use circuits to identify the I-V characteristics of filament lamps, diodes and resistors
Investigating the current-voltage (I-V) graphs of common circuit components Aim: To use circuit diagrams to construct appropriate circuits to investigate the I-V characteristics of a variety of circuit elements, including a filament lamp, a diode and a resistor at constant temperature. |
Background information: Some components like resistors, their resistance does not change as the applied voltage is increased. Some components do not have a constant resistance. This practical investigation explores how the resistance of resistors, diodes and filament lamps vary as the applied voltage is varied. |
Variables:
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Which instrument is used to measure the current in the circuit?
power supply
ammeter
variable resistor
voltmeter
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What is the purpose of the variable resistor in the circuit?
to measure the current through the filament lamp
to vary the temperature of the filament lamp
to vary the voltage across the filament lamp
to measure the voltage across the filament lamp
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Which of the following components would result in a I-V graph which is a straight line through the origin?
resistor
filament lamp
diode
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Which of the following components allows current to flow in the positive direction but not in the negative direciton?
filament lamp
diode
resistor
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Draw the I-V characteristic for a filament lamp.
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Why is it important to turn the power supply off between readings?
to avoid getting an electric shock when moving the variable resistor
to prevent wasting electricity
turning off the circuit would make all the other results invalid and you would need to start again
to prevent the temperature of the circuit from increasing
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