For light of wavelength λ, the stopping potential is 3V₀. For wavelength 2λ, it is V₀. If the threshold wavelength is nλ, find n.
Physics · Photoelectric effect and dual nature of matter
JEE Mains Practice

Question

For light of wavelength λ, the stopping potential is 3V₀. For wavelength 2λ, it is V₀. If the threshold wavelength is nλ, find n.

G1 Physics · Accepted Answer

e(3V₀)=hc/λ−φ and eV₀=hc/(2λ)−φ. Subtracting gives 2eV₀=hc/(2λ), and solving for φ gives threshold wavelength λ₀=4λ. Thus n=4.