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In an experiment to measure the variation of the resistance R of a metallic conductor with its temperature θ a student recorded the following data - Leaving Cert Physics - Question 4 - 2015
Question 4
In an experiment to measure the variation of the resistance R of a metallic conductor with its temperature θ a student recorded the following data. | θ (°C) | 15 | ... show full transcript
Worked Solution & Example Answer:In an experiment to measure the variation of the resistance R of a metallic conductor with its temperature θ a student recorded the following data - Leaving Cert Physics - Question 4 - 2015
Step 1
Using the recorded data, plot a graph to show the variation of the resistance of the metallic conductor with its temperature.
Answer
To plot the graph illustrating the relationship between resistance (R) and temperature (θ), follow these steps:
- Label the Axes: The x-axis should represent the temperature θ in degrees Celsius and the y-axis should represent the resistance R in ohms.
- Plot the Points: Using the provided data:
- For θ = 15, R = 6.0
- For θ = 20, R = 6.2
- For θ = 30, R = 6.5
- For θ = 40, R = 6.8
- For θ = 50, R = 7.2
- For θ = 60, R = 7.5
- For θ = 80, R = 8.2
- For θ = 100, R = 8.8
- Draw the Graph: Connect the plotted points with a straight line that shows a good fit for the data.
Step 2
Use your graph to estimate (i) the rate of change of resistance with respect to temperature for the metallic conductor.
Answer
From the graph, the slope can be determined, which represents the rate of change of resistance with respect to temperature. The slope is calculated as:
ext{slope} = rac{ ext{change in } R}{ ext{change in } θ} = 0.033 ext{ Ω/°C}
This indicates that for every degree Celsius increase in temperature, the resistance increases by approximately 0.033 Ω.
Step 3
Step 4
Describe, with the aid of a circuit diagram, how the student carried out this second experiment.
Answer
To describe the second experiment:
-
Circuit Setup: The circuit consists of:
- A power supply/battery to provide voltage.
- A variable resistor to adjust the current.
- An ammeter connected in series to measure the current.
- A voltmeter connected across the filament bulb to measure voltage.
- The filament bulb as the load in the circuit.
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Correct Arrangement: The voltmeter should be placed across the filament bulb, while the ammeter is in series, ensuring accurate measurements.
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Measurement: The student varied the voltage provided by the power supply and measured the corresponding current using the ammeter. Multiple readings were taken to ensure reliability.
Step 5
Use the findings of the first experiment to explain the shape of the graph in the second experiment.
Answer
The findings from the first experiment indicate that the resistance of the metallic filament increases with temperature. In the second experiment, as the voltage increases, the current also initially increases, but the increase is not linear. This behavior is influenced by the resistance:
- Resistance Increases as Current Increases: As the current flows through the filament, it heats up, increasing its resistance.
- Resistance Increases as Temperature Increases: The filament's resistance is dependent on its temperature, thus the shape of the graph curves upwards, reflecting increasing resistance with rising current.