(A) Suppose the maximum safe average intensity of microwaves for human exposure

Question

(A) Suppose the maximum safe average intensity of microwaves for human exposure is taken to be 1.50 W/m2. If a radar unit leaks 10.0 W of microwaves (other than those sent by its antenna) uniformly in all directions, how far away must you be to be exposed to an average intensity considered to be safe? Assume that the power spreads uniformly over the area of a sphere with no complications from absorption or reflection.

(B) What is the maximum electric field strength at this distance?

Note: early radar units leaked more than modern ones do. This caused identifiable health problems, such as cataracts, for people who worked near them.

Question 1 of 1 Physics presanted by Map sapling leaming Suppose the maximum safe average intensity of microwaves for human exposure is taken to be 1.50 W/m2. If a radar unit leaks 10.0 W of microwaves (other than those sent by its antenna) uniformly in all directions, how far away must you be to be exposed to an average intensity considered to be safe? Assume that the power spreads uniformly over the area of a sphere with no complications from absorption or reflection. Number Tm What is the maximum electric field strength at this distance? Number V/m Note: early radar units leaked more than modern ones do. This caused identifiable health problems, such as cataracts, for people who worked near them. Previous Check Answer ) Next Exit Hint

Explanation / Answer

I = P / 4 pi R^2

Imax = 1.50 W/m^2

P = 10 W

1.50 = 10 / (4 x pi x R^2)

R = 0.728 m ......Ans

I = c e0 E^2 / 2

1.50 = (3 x 10^8)(8.854 x 10^-12) E^2 / 2

E = 10627.5N/C

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