Intensity From a Point Source

In summary, the conversation discusses a point-like source of electromagnetic waves radiating power uniformly in all directions at a single frequency. At a distance of 5.6 km from the source, a detector measures the intensity of the wave to be 35.1 μW/m2. The task is to calculate the amplitude of the magnetic field oscillations at the detector and the total power radiated by the source. The relevant equations and a hint are provided. After solving, the correct answers are 0.163 T for the amplitude and 1.425E-12 W for the total power. The solution involves finding the surface area of a sphere with a given radius and using the intensity to calculate the power. With these values, both
  • #1
Ryo124
101
0

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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  • #2
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!
 
  • #3
Alright, I got a). I cannot figure out b) though.
 
  • #4
Thanks mgb. I got both parts
 

What is intensity from a point source?

Intensity from a point source is a measure of the amount of energy per unit time passing through a unit area, originating from a single point source.

How is intensity from a point source calculated?

Intensity from a point source is calculated by dividing the power of the source by the area through which the energy is passing. This is represented by the equation I = P/A, where I is intensity, P is power, and A is area.

What factors affect the intensity from a point source?

The intensity from a point source can be affected by distance from the source, the angle at which the energy is received, and any obstacles or materials that may absorb or scatter the energy.

What are some real-world applications of intensity from a point source?

Intensity from a point source is used in fields such as astronomy, optics, and acoustics to measure the power and direction of energy coming from a single source. It is also used in medical imaging to measure the intensity of X-rays and other forms of radiation.

How can intensity from a point source be measured?

Intensity from a point source can be measured using specialized instruments such as radiometers, photometers, and sound level meters. These instruments are designed to measure the energy or power passing through a specific area and can provide accurate readings of intensity from a point source.

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