Answer:
f = 7.5 E14 s-1
Explanation:
energy emitted by photon:
∴ λ = (400nm)(m/1 E9 nm) = 4.00 E-7 m
∴ h ( Planck's constant) = 6.626070150 E-34 J.s
∴ c (velocity of light) = 3.00 E8 m/s
∴ f (frequency): photon/s
If (1) = (2):
⇒ f = c / λ = E / h
⇒ f = (3.0 E8 m/s) / ( 4.00 E-7 m) = 7.5 E14 s-1