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# Cellular phone vs. microwave oven

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The average output power of a GSM cellular phone is 1.0W when it is "ON". The phone can be treated as a point source of E-M waves emitting spherical waves.

(a) Calculate the intensity and peak electric field E(max) of the phone's E-M waves in your brain, which is about 5.0cm away from the phone when it is applied directly against year ear.

(b) What is the intensity and peak electric field of E-M wave inside a microwave oven, whose area of cross-section is A=0.25m x 0.30m and the average E-M wave power is 500-W.

(c) How the electric field in (a) compares with the safety regulation of EPA for microwave oven, which says that leaking of more than 5% of the E-field from the oven is harmful to the human body.

https://brainmass.com/physics/applied-physics/cellular-phone-microwave-oven-603665

## SOLUTION This solution is FREE courtesy of BrainMass!

a. Intensity,
I = P/(4pi r^2) = 1/(4*pi*0.05^2) = 31.83 W m^-2

I = c e0 E^2
=> E = sqrt(I/c e0) = sqrt(31.83 / (3*10^8 * 8.86*10^-12)) = 109.43 V m^-1
Peak electric field,
Emax = E*sqrt(2) = 154.76 V m^-1

b. Intensity
I = P/A = 500 / (0.25*0.3) = 6666.67 W m^-2
Peak electric field,
Emax = sqrt(2I /c e0) = sqrt(2*6666.67 / (3*10^8 * 8.86*10^-12)) = 2239.71 V m^-1

c.5% of Emax(oven) = 0.05*2239.71 = 111.99 V m^-1

Microwave oven is safer than a cellular phone near ears.

This content was COPIED from BrainMass.com - View the original, and get the already-completed solution here!