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

AI Thread Summary
The discussion revolves around calculating the amplitude of the magnetic field and the total power radiated by a point-like source of electromagnetic waves. A detector at 5.6 km measures an intensity of 35.1 μW/m². The amplitude of the magnetic field oscillations is derived from the intensity using the provided equations, but initial attempts yielded incorrect results. The total power radiated by the source can be calculated using the intensity and the surface area of a sphere with a radius of 5600 m. The conversation concludes with the original poster successfully solving both parts of the problem.
Ryo124
Messages
101
Reaction score
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.
 
Physics news on Phys.org
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
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Electric field amplitude question regarding intensity calculations
Replies
4
Views
1K
Intensity and electric field amplitude
Replies
7
Views
2K
Calculating τ by knowing I is proportional to A^2
Replies
8
Views
2K
Maximum electric field from magnetic field
Replies
12
Views
3K
Why is source force + electrostatic force = 0 inside battery?
Replies
10
Views
1K
What is the amplitude of induced EMF in a magnetic dipole antenna?
Replies
3
Views
2K
What Is the Correct Source Voltage Amplitude for Desired Power in an AC Circuit?
Replies
19
Views
6K
Calculating Electric and Magnetic Field amplitude
Replies
23
Views
15K
Peak amplitudes of E and H fields (Poynting Vector)
Replies
3
Views
2K
Sound waves and amplitudes Problem
Replies
2
Views
2K

Hot Threads

Recent Insights

Back
Top