Answer:
2.13 x 10^-19 J or 0.53 eV
Step-by-step explanation:
cut off wavelength, λo = 700 nm = 700 x 10^-9 m
λ = 400 nm = 400 x 10^-9 m
Use the energy equation
Where, K be the work function
K = 2.13 x 10^-19 J
K = 0.53 eV
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