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What is the electric field amplitude 2m from the source

1. Homework Statement
A 60 W monochromatic point source is radiating equally in all diresctions in a vacum. What is the electric field amplitude 2m from the source.


2. Homework Equations
Intensity=Power/(4*Pi*r^2), Intensity proportional to square Amplitude


3. The Attempt at a Solution
I=1.19 Wm-2 what happens next?
 

Answers and Replies

Meir Achuz
Science Advisor
Homework Helper
Gold Member
2,169
63
Use I=(1/2)\epsilonzero c E^2.
 
Desperate semi related question. If you have a graph of log intensity against log of (voltage across an LDR in a potential divider circuit)
how do you explain the relationship if your resultant is a straight line of -1.7 obviously in the form of y=mx+c
Log(y)= nlog(x) + logm where y is intensity and x is voltage n being -1.7 and logm being y intercept.
im trying to explain the relationship between the two quantities and ... im stuck if anyone can help me i would very much appreciate it...
 
cristo
Staff Emeritus
Science Advisor
8,056
72
Desperate semi related question. If you have a graph of log intensity against log of (voltage across an LDR in a potential divider circuit)
how do you explain the relationship if your resultant is a straight line of -1.7 obviously in the form of y=mx+c
Log(y)= nlog(x) + logm where y is intensity and x is voltage n being -1.7 and logm being y intercept.
im trying to explain the relationship between the two quantities and ... im stuck if anyone can help me i would very much appreciate it...
Welcome to PF, hopeless blonde. In future, however, please don't hijack another person's thread with your own question-- instead, start a new thread in the relevant homework section.

With regard to your question, you have an equation of the form logy=nlogx+logm. Now, nlogx can be expressed as log(xn). Do you know a rule for loga+logb?
 

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