If the work function of a photometal is 6.825 eV. Its threshold wavelength will be (c=3×108 m/s)
1200 ∘A
1800 ∘A
2400 ∘A
3600 ∘A
λ0=123756.825=1813 ∘A≈1800 ∘A
The work function of a metal is 4.2 eV, its threshold wavelength will be