Power in beam of light given amplitude


by Cspeed
Tags: amplitude, beam, light, power
Cspeed
Cspeed is offline
#1
Dec20-12, 04:08 PM
P: 44
I would like to calculate the power of a beam of light once I know the electric field amplitude. For example if I know the amplitude along a line from -1 meter to +1 meter every 0.5 m is [1, 2, 2.5, 2, 1 V/m], how can I find the power from this is? Is there enough info? (it's in vacuum/air) Thank you.
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
mfb
mfb is offline
#2
Dec20-12, 05:30 PM
Mentor
P: 10,824
Energy density is proportional to the squared amplitude (see Wikipedia for example), and power is just average energy density times the speed of light. Don't forget the magnetic component, which is 50% of the total power.
Cspeed
Cspeed is offline
#3
Dec20-12, 05:43 PM
P: 44
Thanks, but I'm not sure still. I knew that power was proportional to the square of amplitude, but I'm hoping to get a figure in watts. I see that I need H as well. But how does this all fit in to my 1-D scenario?

mfb
mfb is offline
#4
Dec20-12, 05:45 PM
Mentor
P: 10,824

Power in beam of light given amplitude


You get W/m^2 - what else did you expect? If the source emits radiation uniform in space, you can multiply that with the corresponding sphere surface area to get the total power.


Register to reply

Related Discussions
Energy of incident of light to amplitude of light? Introductory Physics Homework 1
Do Light Waves Have Amplitude? General Physics 44
Relationship power and amplitude General Physics 21
Re: Light Amplitude General Physics 0
Power and Amplitude of sound wave Engineering, Comp Sci, & Technology Homework 1