Question

At what temperature a hot body emits uv radiation

Answer 1

The wavelength of light that is radiated from an object depends upon the temperature of the object. The sun is very hot so it emits radiation at many different wavelengths. The surface can be approximated as a blackbody at 6000 K. A normal orange flame may burn at 600 K or so. It isn't hot enough to radiate UV rays but it does radiate in the visible and infrared parts of the electromagnetic spectrum.

Answer 2

All objects with a temperature above absolute zero (0 K, -273.15 oC) emit energy in the form of electromagnetic radiation. A blackbody is a theoretical or model body which absorbs all radiation falling on it, reflecting or transmitting none.