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A student was asked to investigate the variation of current with potential difference for a thin metallic conductor - Leaving Cert Physics - Question 4 - 2013
Question 4
A student was asked to investigate the variation of current with potential difference for a thin metallic conductor. The student set up a circuit using appropriate e... show full transcript
Worked Solution & Example Answer:A student was asked to investigate the variation of current with potential difference for a thin metallic conductor - Leaving Cert Physics - Question 4 - 2013
Step 1
Draw and label the circuit diagram used by the student.
Answer
The circuit diagram used includes:
- A power supply (battery) connected to a voltmeter.
- An ammeter connected in series with the conductor.
- The conductor itself, which in this case is a thin metallic wire, connected in parallel with the voltmeter. Make sure to label all components clearly in the diagram.
Step 2
Name the device in the circuit that is used to vary the potential difference across the conductor.
Answer
The device used to vary the potential difference is a variable resistor (also known as a rheostat or potential divider). This device allows the user to adjust the resistance in the circuit, thereby changing the potential difference across the conductor.
Step 3
Explain how the student used this device to vary the potential difference.
Answer
The student used the variable resistor to alter the resistance in the circuit. By adjusting the slider on the rheostat, the student could increase or decrease the resistance, which directly changed the voltage across the conductor. This means that through this adjustment, a range of potential differences could be applied to the conductor, allowing for the collection of corresponding current values.
Step 4
Use the data in the table to draw a graph on graph paper to show the variation of current with potential difference.
Answer
To draw the graph:
- Label the x-axis as 'Potential Difference (V)' and the y-axis as 'Current (I)'.
- Plot the points corresponding to the values in the table:
- (1.0, 0.17)
- (2.0, 0.34)
- (3.0, 0.50)
- (4.0, 0.64)
- (5.0, 0.77)
- (6.0, 0.88)
- Connect the points and ensure to keep a consistent scale for both axes.
- Use appropriate graphing techniques to depict the data clearly.
Step 5
Use your graph to find the value of the resistance of the conductor when the current is 0.7 A.
Answer
From the graph, find the point where the current is 0.7 A. Read the corresponding potential difference (V) from the graph. Using Ohm's law, the resistance can be calculated as: Substituting the values:
- If V is found to be approximately 4.5 V for I = 0.7 A, then:
Step 6
Explain the shape of your graph.
Answer
The graph shows a linear relationship between current and potential difference, indicating that the resistance is constant throughout the range of values measured. This behavior is consistent with Ohm's law, which states that the current through a conductor is directly proportional to the voltage across it, provided the temperature remains constant. Thus, as the potential difference increases, the current also increases linearly, demonstrating that the resistance of the conductor is stable.