Cellular phone vs. microwave oven
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.
© BrainMass Inc. brainmass.com December 24, 2021, 11:48 pm ad1c9bdddfhttps://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.
© BrainMass Inc. brainmass.com December 24, 2021, 11:48 pm ad1c9bdddf>https://brainmass.com/physics/applied-physics/cellular-phone-microwave-oven-603665