a) The intensity of a light beam I is the product of the light field’s energy de
ID: 958896 • Letter: A
Question
a) The intensity of a light beam I is the product of the light field’s energy density and the velocity of light, namely
where F is the light’s electric field strength. Calculate it for an intensity of 100. W/cm2.
b) The electric field experienced by a valence electron in a molecule, can be estimated as
where d is the distance from the nucleus and q is the shielded nuclear charge, which the valence electron experiences. Use typical values for a ?-electron on a carbon atom (let d = 75 pm and q = ?3.25e), which are appropriate for the pz-orbital on carbon, and calculate the field strength.
c) Compare the two field strengths. Is it reasonable to assume that the light field is small compared to the molecular field?
Explanation / Answer
This is physics, however, let me answer here:
For question 1, you need the value for Eo which is: 8.85x10-12 so:
I = cEoF2 / 2
F = (2I/cEo)1/2
F = (2 * 100 / 3x108 * 8.85x10-12)1/2
F = 274.46 N
For question 2:
F = 9x109 * 3-25*1.6x10-19 / (75x10-12)2
F = 8.32x1011 N
Hope this helps
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