Verification of Joule's Law (Heat produced is proportional to current squared)
When a current flows through a heating element which is immersed in water in a calorimeter the temperature of the water rises. In this experiment we investigate how the temperature of the water and calorimeter change with the current flowing through the heating element. Note: In the lab. this is a very time consuming experiment as each different current must be allowed to flow for at least 5 minutes. In this simulation 60 seconds is sufficient for each current.
Procedure:
- Note the starting temperature and current
- Press "Add Water". Each time this button is pressed the same amount of water is added to the calorimeter.
- Press "Close Switch". Current begins to flow in the heating coil and the timer starts. Note: A very small rise in temperature occurs when the current is at 1A.
- After 60s, press "Open Switch". Record the rise in temperature
- Press "Reset" and "Add Water" and drag the arrow on the variable resistor to a new position. Note the temperature and current.
- Repeat steps 3 to 5 until at least six readings have been taken.
Analysis:
Draw a graph of rise in temperature (y-axis) against current squared to determine the relationship between them. Start at (0,0).
Precautions:
- Ensure that the current remains constant at each value. Adjust the variable resistor if necessary
- Ensure that the heating coil is completely covered with water to avoid heat loss as measured by the thermometer
- Use a well insulated container
- Stir before taking temperature readings and take the highest value observed
