# Infra rays question

1. Oct 20, 2004

### no idea

which one's infra rays wavelength are longer, sun or human body?

2. Oct 20, 2004

### HallsofIvy

What do you mean by "infra" rays?? The only "infra" I know applied to wavelength is infrared radiation which has a fixed range of wavelengths no matter where it comes from.

3. Oct 20, 2004

### spacetime

infra-red rays

Waves are basically classified on the basis of wavelength ( or frequency ). Infra-red rays is the name for the rays having a particular range for wavelengths. So, it doesn't matter what the source of the rays is. If the wavelength falls in the range, they are called infra-red rays.

spacetime
www.geocities.com/physics_all/index.html

4. Oct 20, 2004

### Vector Sum

This sounds like one of those "flawed" questions that come from a lower-level (elementary or junior high) textbooks. I'm guessing that what the question is getting at is:
"which produces more high-energy infra-red rays, the sun or a human body." I'm sure you could guess which one.

THen, what you need to know is that "high energy" infra-red is "shorter wavelength" infra red. Take it from there.