What is the Amplitude of the Magnetic Field for a Point Source?

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Homework Help Overview

The problem involves a point-like source of electromagnetic waves that radiates power uniformly. The context includes measuring the intensity of the wave at a distance from the source and calculating the amplitude of the magnetic field oscillations and the total power radiated by the source.

Discussion Character

  • Exploratory, Problem interpretation, Assumption checking

Approaches and Questions Raised

  • Participants discuss the relationship between intensity, electric field amplitude, and magnetic field amplitude. There are attempts to calculate the total power based on the intensity and surface area of a sphere.

Discussion Status

Some participants have made attempts to solve both parts of the problem, with varying degrees of success. There is acknowledgment of incorrect results and hints provided regarding the calculations needed for total power based on intensity.

Contextual Notes

Participants are working with specific values for intensity and distance, and there is mention of using constants like epsilon. The discussion reflects uncertainty in calculations and the need for further clarification on the relationships between the variables involved.

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Homework Statement



A point-like source of electromagnetic waves radiates power uniformly in all directions at a single frequency.

At a distance of 5.6 km from the source, a detector measures the intensity (energy flux density) of the wave to be 35.1 μW/m2 (microwatts per square meter).

a)Calculate the amplitude of the magnetic field oscillations of the wave at the detector.

b)What is the total power radiated by the source?

Hint: The intensity (power/area) is c ε0 E0^2/2 where E0 is the amplitude of oscillation of the electric field in the wave. Then the magnetic field is B0=E0/c.

Homework Equations



The relevant equations are given in the "Hint" of the problem. And I used 8.85E-12 for epsilon.

The Attempt at a Solution



I got 0.163 T for the amplitude, but it is wrong. I got 1.425E-12 W for the power, but it is also wrong. Help please.
 
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The power is easy, what is the surface area of a sphere wih radius = 5600m,
If the intensity is 35.1E-6w/m^2 what is the total power for this area, hint the units should come out as watts!
 
Alright, I got a). I cannot figure out b) though.
 
Thanks mgb. I got both parts
 

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