demonstrations:exploring_infrared_radiation_with_a_heat_lamp

Exploring Infrared Radiation with a Heat Lamp

Materials: ★★★ Requires materials not commonly found in school laboratories
Difficulty: ★★☆ Can be done by science teachers
Safety: ★★☆ Some safety precautions required to perform safely

Categories: Electromagnetic Spectrum and Waves, Heat

Alternative titles: Feeling Invisible Heat

Summary

This demonstration allows students to feel the warming effect of infrared (IR) radiation from a heat lamp. By placing different materials such as glass, plastic, and aluminum foil between the lamp and their hands, students can observe which materials block or transmit IR radiation.

Procedure

  1. Set up an infrared heat lamp in a safe, stable position.
  2. Have students hold their hands at a comfortable distance from the lamp to feel the heat.
  3. Place a sheet of glass between the lamp and their hands, and note whether the warming effect changes.
  4. Repeat with a sheet of plastic and then with aluminum foil.
  5. Compare and discuss which materials block or transmit the infrared radiation.
  • None available

Variations

  • Use different types of plastics (clear vs. opaque) to see how transmission changes.
  • Test tinted or coated glass, such as sunglasses lenses or car window glass.
  • Place a thermometer behind each material instead of a hand to collect quantitative data.
  • Compare IR blocking with visible light transmission (e.g., foil blocks both, glass transmits visible but blocks some IR).

Safety Precautions

  • Do not touch the heat lamp, as it becomes very hot.
  • Keep flammable materials away from the lamp.
  • Limit exposure time to avoid burns or discomfort.
  • Use protective stands or holders for materials instead of students holding them close to the lamp.

Questions to Consider

  • Why can we feel the heat from the lamp even though we cannot see infrared radiation? (Because IR radiation carries energy that is absorbed by our skin as heat.)
  • Which materials blocked the IR radiation most effectively? Why? (Aluminum foil reflects IR completely, while glass and some plastics allow partial transmission.)
  • How does this experiment relate to real-world applications such as window coatings or thermal blankets? (These materials are designed to block or reflect infrared radiation to control heat transfer.)
  • How does infrared radiation differ from visible light? (It has longer wavelengths, is invisible to the human eye, but is detected as heat.)