Investigating infrared radiation

Question 1

Amount of IR does not just depend on the temperature but also ————–

Answer 1

material of surface

A Leslie cube is hollow, water tight and 4 vertical faces have different surfaces . You can use this to investigate IR emission by different surfaces

Question 2

Practical 1 -3

Answer 2

1) Place empty Leslie cube on heat proof mat
2) boil water with kettle and fill Leslie cube with boiling water
3) wait a while for cube to warm up and then hold thermometer against each of 4 faces of vertical cube and you can see all 4 faces have same temp

Question 3

Practical 4-6

Answer 3

4) Hold infrared detector a set distance away from one of cubes vertical faces and record amount of IR radiation it detects

5) Repeat this for each face of cube making sure detector is at same distance from cube each time

6) You should find that you detect more IR radiation from black surface then white
and more from matt than shiny

Question 4

Practical 7-8

Answer 4

7) repeat experiment to make sure your results are repeatable

8) Safety precautions = don’t move Leslie cube when its got boiling water in it, and you may burn your hands when carrying full kettle

Question 5

Investigate absorption with melting wax trick - amount of absorption depends on material PRACTICAL 1

Answer 5

1) set up equipment , two ball bearings are stuck to a metal plate with solid pieces of candle wax
Other side of plate faced towards flame

Sides facing flame have different surface colour - one matte black and one silver

Question 6

Investigate absorption with melting wax trick - amount of absorption depends on material PRACTICAL 2

Answer 6

ball bearing on black surface falls first as it absorbs more IRR- transferring more energy to thermal energy store of wax

= wax on black plate will melt first before wax on silver plate