Take Home Lab #4

Take Home Lab #4:  Finger Thermometer

Question: Can your finger be used as an accurate thermometer?

Safety: Only warm water and refrigerator-cold water should be used for this activity. If the activity becomes uncomfortable at any time, stop immediately. Clean up any spills to prevent slipping and falling.

Materials: 3 cups with cold water, room temperature water, and warm water

Procedure: You can put your finger in a cup of water and determine if it is hot or cold. But how accurate is your finger as a thermometer? In this activity, you will find out if your finger is more of a temperature detector or a detector of changes in temperature.

1. Get three drinking cups ready with a wide enough mouth that allows you to put your finger in the water.

2. In the left cup, put cold water either from the refrigerator or tap water with a couple of ice cubes in it. In the middle cup, put room-temperature tap water. In the right cup, put warm tap water.

3. Put a finger from your left hand in the left (cold) cup and put your right finger in the right (warm) cup of water. Wait 30 seconds, then put both fingers in the middle cup. Think about how the water feels to each of the fingers.

Post-Lab Questions:

1. How did the water feel to your left hand? How did the water feel to your right hand?

2. Is your skin a temperature detector or a change-in-temperature detector?

3. How is this similar to the optical illusions where you stare at a colored object for 30 seconds and then stare at a blank wall? If you have not seen on of these before, use your favorite online search engine to search for “American Flag Optical Illusion.”

Part 2:

Procedure:

Find a smooth object (such a sheet protector, plastic cover of a composition book, or other smooth piece of plastic) and a sheet of paper. Set the smooth object near carpet. For 30 seconds, rub the fingers of your left hand on the carpet and the fingers of your right hand on the smooth object. After 30 seconds, rub the fingers of both hands on the sheet of paper.

Post-Lab Questions:

1. How does the paper feel to your left hand? How does it feel to your right hand?

2. How is this similar to the finger thermometer?