Heat radiation lamp

Use an infrared heat lamp to demonstrate heat transfer by radiation. Add in heat sensitive sheets to add in heat transfer by conduction.
Science content
Physics: Heat (3)
Lessons activity is in
  • infra red lamp, 250W, like this one - 3 for a class
  • fixtures for the lamps, with extension cords
  • small sheet of glass
  • small sheet of plexi
  • cardstock
  • small piece of foam core
  • optional (be careful): garbage bag
  • plastic box
  • water
  • mirror
  • not essential but adds a free play element: heat sensitive sheets
  • shields to keep students at least 20cm from the lamps (so they don't destroy the heat sensitive sheets) - cardboard shield idea pictured
  • IR images (see procedure for links)

Note: parts of this activity are in proto type stage (indicated)

Heat radiation demonstration
Use an infra red heat lamp on an upright fixture, so the teacher can pick it up, and it can also be stood upright in the centre of a circle of students.
(An indandescent bulb also gives off a lot of heat, mostly by radiation. 1/8 of its heat energy is by conduction and convection.)
Turn the lamp on and walk past the students so that they can feel the heat coming from the bulb.
Tell them that this lamp gives off some light (which we can see) and also heat (which we can't see).
The heat is called radiation, and is a kind of radiation called Infra red. (Some other kinds of radiation (visible and UV) can heat things up.)
Although we can't see heat radiation, we can still sense it - we can feel it.
The sun gives off radiation. Radiation can travel through space with no air. (The other kinds of heat movement, conduction and convection, need particles of matter to happen.)

Look at IR images together
Many materials give off radiation.
House: or…
Water rescue (scroll down):…
Andromeda galaxy (4th image down):

Demo: Heat radiation can pass through some materials and not others
Use heat sensitive paper to show heat. As it heats up the heat sensitive sheet turns from black to red, orange, yellow, green, blue, then black again. Demonstrate that the sheet turns colours when placed near the infra red heat lamp.
Does radiation pass through glass - do you get warm through a window? (It might be hard to remember, or separate what you remember from what you think should happen.) [Yes] Show with the heat sensitive sheet on the other side of the glass from the lamp.
Does radiation pass through plastic? Show with plexi sheet. [Yes]
Cardboard? [No]
Through water? Show it does pass through the plastic box, then add water to the box.

Just like visible light, infra red heat radiation can bounce off mirrors.
Hold the mirror so that infra red from the heat lamp reflects off the mirror and onto the heat sensitive sheet.

Free play radiation and conduction
Before the lesson: Space the the heat lamps around the classroom, minimizing wires to be tripped over (as students will be walking around the classroom a lot).
Before the lesson: Set up a shield so that the students cannot bring a heat sensitive sheet closer than 20cm to the lamp (not prototyped yet).
Hand heat sensitive sheets to students, and allow them to explore them for a while.
Discuss how heat moves from your hand to the sheet, to make it turn colours. Your hand and the sheet are touching - the heat moves between them by conduction.
Air is also touching the sheet and conducts heat away from it - there are molecules in the air that bounce into the sheet and take some of its energy and cool it down again.

Show students how to charge their sheet with the radiation from the heat lamp. Include a shield around the lamp (idea pictured), so students don't hold them too close and destroy them.
Then quickly touch it to materials in the classroom, to see how the heat leaves the sheet by conduction. Make sure the coloured side of the sheet is up, so you can see it change.
Allow students to explore.
After the radiation from the heat lamp heated the sheet up, which materials in the classroom conducted the heat away quickly, and which ones slowly? What patterns did you make on your heat sensitive sheets, when different parts of an object took heat away at different rates?


Need half hour to set up heat lamp charging stations for heat sensitive sheets

Grades taught
Gr 2
Gr 3
Gr 4