JEE Main levelNumerical answerDifficulty 2 of 3as023
Ultraviolet light of wavelength 260nm falls on a metal of work function 2.1eV. Find the maximum kinetic energy of the photoelectrons in eV, to two decimals. Use h=6.626×10−34Js, c=3.0×108ms−1, 1eV=1.6×10−19J.
Numerical answer type, answer in eV, tolerance 0.02.
Answer: 2.68 eV
Photon energy = hc/λ = 7.6454e-19 J = 4.778 eV. Kmax = E - W = 4.778 - 2.1 = 2.68 eV.