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Infrared radiation

Part II - Absorption

 

Objectives

• Be able to compare the effectiveness of different surfaces as absorbers, by considering the nature of the surface.

• Be able to describe and explain how these properties are used to design more effective appliances and buildings.

 

 

 

 

Task 1

We are going to carry out an experiment to investigate how different surfaces absorb infrared radiation, using the following equipment:

 

2 x conical flasks (1 black, 1 silver)

2 x thermometers

1 x stopwatch

1 x radiant heater

 

Your teacher will demonstrate how the apparatus is set up.  Draw a labelled diagram in your exercise book and a table to record the results.

 

 

Task 2

Work out the increase in temperature for each flask.  Make a note of your findings by copying and completing the sentences below:

 

The temperature of the silver flask increased by ______ ˚C.

The temperature of the black flask increased by ______ ˚C.

 

In our last experiment we found that ________, ________ surfaces emitted infrared radiation more effectively than _________, ________ surfaces.  The results of this experiment have shown us that __________, ________ surfaces are also more effective at _____________ infrared radiation.

 

We can conclude that good __________ of infrared radiation are also good _________ of infrared radiation!

 

 

 

 

Task 3

Answer the questions below:

1. Why are teapots often shiny?
2. Why are buildings in the Mediterranean often painted white?  How does this help to keep the houses cool in the summer?
3. Why does a patio heater have a shiny surface on top? Pc_pic_007