Why Can You See Objects Under a Heat Lamp?

Heat lamps are often used to keep food warm.

Heat lamps are a low-cost option for heating quickly. They use a bulb to emit infrared electromagnetic radiation, which heats the objects it encounters. Just as incandescent light bulbs produce some heat as a byproduct, infrared bulbs produce some light as a byproduct.

Visible Light vs. Infrared Light

Heat lamps are similar to regular lamps, but they emit different wavelengths. Visible light is exactly the same type of energy as infrared light, and the two are next to each other on the electromagnetic spectrum, but the wavelengths of visible light are shorter than those of infrared light.

Infrared Emissions

According to Global Spec.com, heat lamps are designed to emit light in the near infrared, middle infrared, far infrared and far-far infrared ranges, which include wavelengths from 0.7 to 1000 micrometers. Visible light is between 0.7 and 0.4 micrometers in wavelength. Because they are so similar in size, some overlap occurs.

Heat Lamp Bulbs

Heat lamps use different filaments in their bulbs than standard light bulbs. The filaments in heat lamps are designed to emit more infrared radiation and less visible light than standard bulbs, but because the two types of light are so close together on the electromagnetic spectrum, there is some overlap in this area as well, allowing people to see in the light of a heat lamp.

References

• Global Spec: About Heat Lamps
• University of Tennessee: The Electromagnetic Spectrum