Δp for total reflection and absorbtion of E&M radiation explanation?


by Phyzwizz
Tags: Δp, absorbtion, eandm, explanation, radiation, reflection
Phyzwizz
Phyzwizz is offline
#1
Apr18-13, 11:43 AM
P: 54
The equation for the change in momentum for total absorption of electromagnetic radiation is ΔU/c and that for total reflection is (2ΔU)/c. How could the momentum of electromagnetic radiation change if it is massless and travels at a constant speed c? Is the ΔU just a representation of a change in the frequency of the radiation? Also my book does a poor job in explaining the reason that the change in momentum is double for total reflection (perhaps this will become more clear with an explanation of the previous questions).Δ
Phys.Org News Partner Physics news on Phys.org
Physicists design quantum switches which can be activated by single photons
'Dressed' laser aimed at clouds may be key to inducing rain, lightning
Higher-order nonlinear optical processes observed using the SACLA X-ray free-electron laser
technician
technician is offline
#2
Apr18-13, 12:46 PM
P: 1,506
The change in momentum for reflection is 2 x thechange for absorption for the same reason that the change in momentum for a ball hitting a wall and stopping dead is mv but a ball rebounding with the same speed has a change in momentum of 2mv. Momentum changes from +mv to -mv.
virtuosowanaB
virtuosowanaB is offline
#3
Apr21-13, 01:07 AM
P: 6
Complete Reflection

Δp = ΔU/c - (-ΔU/c) = 2(ΔU/c)


Register to reply

Related Discussions
The relationship between absorbtion, emissivity and reflection Classical Physics 1
Absorbtion,reflection,and emission. General Physics 1
Transmission, reflection, and absorbtion General Physics 2
reflection and absorbtion Atomic, Solid State, Comp. Physics 5
Absorbtion and Reflection of Objects, question General Physics 2