The frequency of particular radiation is 0.42 × 10¹⁵/s. Find its wavelength in nm. 

λ = c / ν  

(1 nm = 10−9 m) 

c = velocity of light = 3 × 10⁸ m/s 

λ = c / ν  

= 3 × 10⁸/0.42 × 10¹⁵ 

= 7 × 10^–7m = 700nm