Question

Find out the longest wave length of light just able to eject a least bound electron from copper ( work function = 4.3 ev

Answer 1

hc/k = 4.3 + K.E

take K.E. = 0

(for longest wavelength)

therfore,

k = hc/4.3 = 1240/4.3 = 288.3872 nm

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