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In an experiment to verify Joule's law, a heating coil was placed in a fixed mass of water - Leaving Cert Physics - Question 4 - 2016
Question 4
In an experiment to verify Joule's law, a heating coil was placed in a fixed mass of water. A current I was allowed to flow through the coil for a fixed length of t... show full transcript
Worked Solution & Example Answer:In an experiment to verify Joule's law, a heating coil was placed in a fixed mass of water - Leaving Cert Physics - Question 4 - 2016
Step 1
Draw a labelled diagram of the arrangement of the apparatus used in this experiment.
Answer
To draw the labelled diagram of the apparatus:
- Start with a heat source (such as a heating coil) in the center.
- Connect this to a voltmeter and an ammeter to measure voltage and current, respectively.
- Include a calorimeter filled with a fixed mass of water surrounding the heating coil.
- Ensure all parts are labelled, including the water, heating coil, ammeter, voltmeter, and power supply.
Step 2
How was the current changed during the experiment?
Answer
The current was adjusted by manipulating the variable resistor in the circuit. This allowed the experimenter to control the amount of current flowing through the heating coil, which was essential to observe the resulting temperature changes in the water.
Step 3
Step 4
Using the data in the completed table, draw a graph on graph paper of Δθ against I².
Answer
- Label the x-axis as I² (in A²) and the y-axis as Δθ (in °C).
- Plot the data points for Δθ against I² calculated from the table.
- Connect the points with a straight line to show the relationship clearly.
Step 5
Explain how your graph verifies Joule's law.
Answer
Joule's law states that the heat generated is proportional to the square of the current flowing through the conductor, defined by the formula: .
In the graph, as I² increases, Δθ increases proportionally, confirming that the heat generated by the coil is indeed proportional to the square of the current, thereby verifying Joule's law.