STUDENT INSTRUCTION AND ANSWER
Activity 4: How Hot Does Your
Your Mom bought two identical potatoes at the store. She put one potato in a cold freezer, and the other potato in a warm oven. Some time later she took the potatoes out of the freezer and the oven and placed them down on the table.
A. Could you tell which potato is cold and which one is hot by just looking at them? Explain why or why not.
B. Could you tell which potato is cold and which one is hot if you were to hold them in your hands? Explain why or why not.
Now imagine that you could not get close enough to the potatoes to hold them, but still wanted to determine which was hot and which was cold. This is the type of problem that is encountered when one does remote sensing.
Consider the two pictures shown below. Picture 1 comes from a camera that is sensitive to visible light like our eye. Picture 2 comes from a camera that is sensitive to only infrared light (not visible light.) Scientists look at the infrared light emitted by an object because this form of emitted light is closely related to the temperature of the object. In a typical infrared picture, objects that appear bright are at higher temperatures and objects that appear dark are at colder temperatures.
Picture 1: Taken with camera sensitive to only visible light.
Picture 2: Taken with camera sensitive to only infrared light.
D. For Picture 2, is the light coming to the camera reflected or emitted light? Is it visible or infrared? Explain your reasoning.
E. Which potato is hot? Which potato is cold? Explain your reasoning.
F. Describe a situation in which both of the potatoes would be invisible to the human eye but not to an infrared camera.
G. Draw a sketch of what the infrared picture would look like the next day after the potatoes were left on the table overnight.
H. Draw a picture that shows what the infrared camera would see if it were pointed at a Styrofoam block and a metal block at the instant each were removed from a freezer that they had been left in overnight.
I. Draw an overhead sketch (looking straight down) of what the satellite on Activity Page Two would detect if it were equipped with an infrared camera.