Question

Name the radiations of wavelength just (a) longer than $8\times {10}^{-7}m,$ (b) shorter than $4\times {10}^{-7}m$.

Answer 1

(a)Infrared radiations are longer than $8\times {10}^{-7}$ m.
(b) ultraviolet radiations are shorter than $4\times {10}^{-7}$ ​​​​​​​m.