Question

A black body radiated maximum energy at wavelength lambda if nlamba the power radiated becomes how many tines

Answer 1

we know that
E=hc/lambda
E is inversely proportional to lambda
if lambda becomes n lambda
then E becomes E/n

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.