Doubt by Nabeela Hameed

Plz explain its answer..

Answers

Answer by Jay Prakash

Request you to focus on NCERT syllabus only. Don't spend time on stuff beyond NCERT syllabus at this time. 

Explanation just in case: Wavelength λk is independent of the accelerating voltage (V), while the minimum wavelength λc is inversely proportional to V. Therefore as V increases, λk remains unchanged whereas λc decreases or λk−λc will increase.