ECE 532, 1. Measuring the temperature rise of the water will yield the power of the light bulb. Prepare a cup of water by adding India ink so it is very black. No light escapes the black cup of water.
All energy is absorbed and heats the water.
Turn the light off after one minute. Stir the water to uniformly distribute the heat and measure the final temperature rise using a digital thermometer. We shall neglect the heat capacity and mass of the cup itself in this calculation. OMLC homepage .