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 90 seconds is sufficient for each current.
- Use the slider to set the current value to 0.5 A.
- Note the starting temperature and current and record in a table.
- Press "Close Circuit". 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 0.5 and 1A.
- After 90s, press "Open Circuit". Record the rise in temperature.
- Press "Reset" and again use the slider to set the current to 1 A. Record the starting temperature and current.
- Repeat steps 3 to 5 until at least six readings have been taken.
Draw a graph, on graph paper, of Rise in Temperature versus Current squared. Start both axes at zero and draw a "best fit" line through the data points.
All Physics Experiments
- 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.