A radio antenna broadcasts a 1.0 MHz radio wave with 23kW of power. Assume that

Question

A radio antenna broadcasts a 1.0 MHz radio wave with 23kW of power. Assume that the antenna emits the radio wave uniformly in all directions

What is the wave's intensity 30km from the antenna?

What is the electric field amplitude at this distance?

MHz

A cell-phone tower broadcasts a 1900  radio wave with 23 of power. Assuming that it also emits uniformly in all directions, how does the intensity of its wave at a distance 30 compare to the intenisty of the radio tower?

The cell phone's intensity will be equal to the radio's intensity.

The cell phone's intensity will be larger than the radio's intensity.

The cell phone's intensity will be smaller than the radio's intensity.

The cell phone's intensity will be equal to the radio's intensity.

The cell phone's intensity will be larger than the radio's intensity.

The cell phone's intensity will be smaller than the radio's intensity.

Explanation / Answer

a)

I = P/4*pi*r^2 = 23000/4*pi*30000^2

I = 2.034 *10^-6 W/m^2

b)

E = sqrt(2*I/C*e0) =sqrt(2*2.034*10^-6/3*10^8*8.854*10^-12)

E = 1.53*10^-3 V/m

c)

The cell phone's intensity will be equal to the radio's intensity.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.