Consider a cell phone that emits electromagnetic radiation with a frequency of 1

Question

Consider a cell phone that emits electromagnetic radiation with a frequency of 1.0 GHz (1.0 x 10^9 Hz) with a power of 1.0W. (a) What is the approximate electric field amplitude at a distance of 1000m from the phone? Assume it radiates with spherical wavefronts. (b) What is the approximate electric field amplitude at your ear as you use the phone? Again assume it radiates with spherical wavefronts. (c) If the phone can be turned on and transmitting for 3 hours before discharging the battery, how much energy can be stored in the battery?

Explanation / Answer

a. I = P/A = Erms^2/u0c

Erms^2 = 1*3*10^8*12.56*10^-7/ 4*3.14*10^6

Erms^2 = 0.3 *10^-6

Erms = 0.54 *10^-3 N/C

b. Emax = 0.77 *10^-3 N/C

c.

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