Required Practical 10

Question 1

What is the aim of this experiment?

Answer 1

Investigate how the amount of infrared radiation absorbed or radiated by a surface depends on the nature of that surface.

Question 2

What is a Leslie cube?

Answer 2

A hollow, watertight metal cube of metal whose 4 vertical face all have different surfaces e.g. matt black, matt white, shiny black and shiny silver.

Question 3

Step 1

Answer 3

Place an empty Leslie cube on a heat proof mat

Question 4

Step 2

Answer 4

Boil water in a kettle and fill the Leslie cube with the boiling water.

Question 5

Step 3

Answer 5

Wait for the cube to warm up and then hold a thermometer against each of the 4 verticle faces of the cube (they should all be the same temp)

Question 6

Step 4

Answer 6

Hold an infrared detector 5 cm away from one of the cubes vertical surfaces and record the amount of IR radiation it detects.

Question 7

Step 5

Answer 7

Repeat this measurement for each of the cubes vertical surfaces ensuring that you position the detector the same distance from the cube each time.

Question 8

Results

Answer 8

You should find that you detect more infrared radiation from the black surface than the white one and more from the matt surfaces than the shiny ones.

Question 9

You should repeat the experiment at least 3 times to determine the accuracy of the method.

Question 10

What is one of the graphs you can plot?

Answer 10

temp on y axis
time one x axis
(results for each different surface)

Question 11

What is another one of the graphs you can plot?

Answer 11

Plot a bar chart of the results. The surface with the greatest infrared emission is the best emitter of infrared radiation. This surface will also be the best absorber of infrared radiation.
(y axis= detector reading)
(x axis = surface)

Question 12

What is a hazard in this experiment?

Answer 12

boiling water

Question 13

What is a consequence of the hazard?

Answer 13

scalds

Question 14

How do we prevent harm?

Answer 14

Pour water slowly, using a funnel if necessary. Do not move the Leslie cube until it has cooled. Avoid spilling water on any electrics of the infrared detector. Goggles

Question 15

What are some control variables?

Answer 15

. distance of detector from Leslie cube
. temp of water
. The Leslie cube used
.The detector used

Question 16

What are some independent variables?

Answer 16

the surface of the Leslie cube

Question 17

What are some dependant variables?

Answer 17

The radiation transmitted/ absorbed