Station 2: Convection – Warm Water Currents

Materials

  • Pitcher of room-temperature water
  • A source of very hot water, such as an electric teakettle, hot plate and regular kettle, or coffee maker (hot tap water is usually not hot enough)
  • Clear plastic plant saucer 8 to 10 inches wide. Caution: DO NOT use saucers with concentric raised rings on the inside bottom; radial ridges are okay
  • Food coloring
  • Small container for food coloring (a small cup would work fine)
  • Medicine dropper or pipette
  • Four Styrofoam cups
  • Data sheet

Procedure

You will conduct two experiments to trace the currents when water is not evenly heated.

  • In the first experiment, you will observe the movement of drops of food coloring in still water.
  • In the second experiment, you will add a heat source and observe the movement of drops of food coloring in the water as it is heated.

Experiment 1

  1. Place three Styrofoam cups upside down on a piece of paper.
  2. Place the plastic plant saucer on top of the cups. The cups should be near the outer edges of the saucer and evenly spaced.
  3. Fill the plastic saucers three-quarters full with room-temperature water. Be careful not to bump the desk or table at any time during the experiment.
  4. Using a dropper, slowly release four drops of food coloring at the bottom of the saucer of water one at the center and one over each of the three cups. Slowly remove the dropper, taking care not to stir the water.
  5. Observe what happens to the drop of food coloring. Draw a diagram in the space provided showing how the drop changes over time.

Experiment 2

  1. Remove the saucer, dump the water in the sink, and rinse out all the dye.
  2. Fill a fourth Styrofoam cup with hot water from the source provided; be sure it’s nearly full! Place the cup in the center of the first three.
  3. Replace the saucer over the four cups and fill it with water as before.
  4. Repeat steps 4 and 5 from Experiment 1.

Observations: Experiment 1

Observations: Experiment 2

Questions:

  1. What effect does the hot water in the center under the saucepan have upon the currents?
  2. What type of heat transfer is taking place? How do you know?

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