2. Greenhouse Effect (Radiation)

An infra-red (IR) thermometer can be used to make some experiments more concrete.

Better still Concord uses affordable IR cameras to visualize invisible energy flows and transformations in easy-to-do science experiments. Using this “desktop remote sensing” approach, thermal energy can be readily “seen.”

Other types of energy that convert into thermal energy can be inferred from thermal signals. Hence, many invisible physical, chemical, and biological processes that absorb or release heat can be visualized, discovered, and investigated. The following experiment can be successfully performed using a simple IR thermometer only.

Shine a desk lamp (or invisible IR light source) through an inverted plastic take-away or similar container.

The light will be absorbed by the black paper inside.

The paper will radiate IR light, but the IR radiation emitted from the paper cannot penetrate through the transparent container.

As a result, heat is trapped inside the cup.

The above can be measured using an IR thermometer.

QUESTION

• What happens to the temperature inside the container - and why?
• How could this experiment be extended/adapted to show a range of other heat-related effects?

PROBLEM Do Different Colours Absorb More/Less Sunlight/Heat?

1. Use a graphics or word processor application to create and print a page with different colour bars
   1. include a black and a white bar/area
   2. make the bars as large as possible to fill the page
   3. make each of the bars the same size
2. Create a simple table to record the temperature for white, black and each of the other printed colours:
3. Place the printed sheet in the clear sunlight for a few miutes.
4. Use an IR thermometer to measure he temperature difference between different colours and enter the results into your table

QUESTION

• If the temperatures vary for different colours, what does this tell you?
• How accurate would the results be, and why?
• Would these results make a difference to colours you would choose for things you use outside?

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