What is the work function of the metal if the light of wavelength 4000 A o generates photoelectrons of velocity 6 × 10 5 ms - 1 from it? (Mass of electron = 9 × 10 - 31 kg , velocity of light = 3 × 10

Question

What is the work function of the metal if the light of wavelength $4000 \overset{o}{A}$ generates photoelectrons of velocity $6 \times 10^{5} {ms}^{- 1}$ from it?

(Mass of electron $= 9 \times 10^{- 31} kg$ , velocity of light $= 3 \times 10^{8} {ms}^{- 1}$ , Planck's constant $= 6 .626 \times 10^{- 34} Js$ , Charge of electron $= 6 .626 \times 10^{- 34} Js$ )

TestHub · Accepted Answer

hc λ = hc λ 0 + 1 2 mv 2 hc λ 0 = hc λ - 1 2 mv 2 = 6.626 × 10 - 34 × 3 × 10 8 4000 × 10 - 10 - 1 2 9.1 × 10 - 31 × 6 × 10 5 2 = 6.626 × 3 × 10 - 19 4 - 9.1 × 6 × 6 2 × 10 - 21 = 4.97 × 10 - 19 - 1.64 × 10 - 19 = 3.33 × 10 - 19 Joule Work function hc λ 0 = 3 .33 × 10 - 19 1 .6 × 10 - 19 = 2 .08 ≈ 2 .1 eV

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