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In an experiment to investigate the variation of resistance with temperature for a metallic conductor in the form of a wire, a student measured the resistance of the conductor at different temperatures - Leaving Cert Physics - Question 4 - 2006
Question 4
In an experiment to investigate the variation of resistance with temperature for a metallic conductor in the form of a wire, a student measured the resistance of the... show full transcript
Worked Solution & Example Answer:In an experiment to investigate the variation of resistance with temperature for a metallic conductor in the form of a wire, a student measured the resistance of the conductor at different temperatures - Leaving Cert Physics - Question 4 - 2006
Step 1
How did the student measure the resistance of the wire?
Answer
The student used an ohmmeter or multimeter to measure the resistance of the wire. This device measures the voltage and current passing through the wire to calculate the resistance using Ohm's Law, which states that resistance (R) is equal to the voltage (V) divided by the current (I): .
Step 2
Describe, with the aid of a diagram, how the student varied the temperature of the wire.
Answer
The student varied the temperature of the wire by using a water bath. The setup included the wire immersed in water, with a thermometer also in the water to measure the temperature accurately. A heat source, such as a hot plate, was used to heat the water, increasing the temperature of the wire, which was monitored continuously.
Step 3
Using the data in the table, draw a graph on graph paper of the resistance of the conductor against its temperature. Put temperature on the horizontal (X-axis).
Answer
To graph the resistance against temperature:
- Label the X-axis as 'Temperature (°C)' and the Y-axis as 'Resistance (Ω)'.
- Plot the data points from the table: (20, 45.6), (30, 49.2), (40, 52.8), (50, 57.6), (60, 60.0), (70, 63.6), and (80, 68.4).
- Ensure each point is plotted correctly according to their respective coordinates.
- Connect the points with a straight line to show the trend.
- If the graph does not start at the origin, mark the lowest temperature and resistance values at their respective axes clearly.
Step 4
Use the graph to estimate the temperature of the conductor when its resistance is 50Ω.
Answer
From the graph, locate the point where the resistance is 50Ω. Draw a horizontal line from 50Ω across to intersect the graph line. Then drop down vertically to the X-axis to read the corresponding temperature. This should give an estimated temperature of around 30-33°C.
Step 5
What does your graph tell you about the relationship between the resistance of a metallic conductor and its temperature?
Answer
The graph indicates a direct relationship between the resistance of a metallic conductor and its temperature. As the temperature increases, the resistance also increases. This can be attributed to the increased thermal energy that causes more collisions between electrons in the conductor, leading to higher resistance.