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stanli121

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## Homework Statement

A radio transmission tower radiates electromagnetic waves uniformly in all directions

with an average total power Pav = 70, 000 W at a frequency f = 98 MHz. A radio

receiver uses the induced emf in a single circular wire loop of radius r = 5.0 cm to

detect a radio signal.

If the maximum induced emf must exceed 0.0050 V to be detectable, find the maximum

distance d the receiver can be from the transmission tower and detect the wave.

(The distance d is much greater than the wavelength of the wave.)

## Homework Equations

S = EB/uo

I = P/4(pi)r^2

I = E(rms)^2/c*uo

E or B are functions given by E(x,t)=Esin(kx-wt) or B(x,t)=Bsin(kx-wt)

c=f(wavelength) and k = 2(pi)/(wavelength)

## The Attempt at a Solution

I started with the end and went for V = -dflux/dt. I found the flux of the B field through the loop and then differentiated B(x,t) wrt time. I have an expression for this but I'm not sure what the B coefficient in the B(x,t) equation (max value of B) should be or what to do about the cos(kx - wt) term. Any help on where to go for this problem?