The diagram shows a circuit used to investigate the variation of current with potential difference for a semiconductor diode in forward bias - Leaving Cert Physics - Question 4 - 2008
Question 4
The diagram shows a circuit used to investigate the variation of current with potential difference for a semiconductor diode in forward bias.
(i) Name the apparatus... show full transcript
Worked Solution & Example Answer:The diagram shows a circuit used to investigate the variation of current with potential difference for a semiconductor diode in forward bias - Leaving Cert Physics - Question 4 - 2008
Step 1
Name the apparatus X. What does it measure?
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Answer
The apparatus X is called a milliameter or galvanometer. It measures current in milliamperes (mA) or in amps (A).
Step 2
Name the apparatus Y. What does it do?
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Answer
The apparatus Y is a variable resistor or a potentiometer. It adjusts the resistance in the circuit, which allows for the measurement of voltage, potential, and current.
Step 3
What is the function of the 330 Ω resistor in this circuit?
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The 330 Ω resistor serves to protect the diode by limiting the current that can flow through it. This helps prevent the diode from being damaged by excessive current.
Step 4
Draw a graph on graph paper of the current against the potential difference.
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To draw the graph, plot the potential difference values along the horizontal X-axis from 0.0 V to 1.0 V and the current values along the vertical Y-axis from 0 to 100 mA. The graph will typically show a curve that increases rapidly at lower voltages and then levels off at higher voltages.
Step 5
What does the graph tell you about the variation of current with potential difference for a semiconductor diode?
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The graph indicates that the current through the diode increases rapidly for potential differences below 0.6 V. Beyond this point, the current increases more gradually, suggesting a non-linear relationship. Specifically, the graph shows that as the potential difference increases, the current also rises significantly but does not increase linearly; rather, it follows an exponential pattern typical of semiconductor diodes.
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