Suppose the maximum safe intensity of microwaves for human exposureis taken to be 1.32 W/m². If a small radar unit leaks 10.0 W ofmicrowaves (other than those sent by its antenna) uniformly in alldirections, how far away must you be to be exposed to an intensityconsidered to be safe? Assume that the power spreads uniformly overthe area of a sphere with no complications from absorption or reflection.(Note that early radar units leaked more than modern ones do. Thiscaused identifiable health problems, such as cataracts, for people whoworked near them.)

Given:Maximum intensity of radiated microwave = 1.32 W/m²Power output of the radar = 10.0W…

Answered: Suppose the maximum safe intensity of…

University Physics Volume 2

18th Edition

ISBN:9781938168161

Author:OpenStax

Publisher:OpenStax

Chapter16: Electromagnetic Waves

Section: Chapter Questions

Problem 62P: Suppose the maximum safe intensity of microwaves for human exposure is taken to be 1,00 W/m2. (a) If...

See similar textbooks

Similar questions

On its highest power setting, a microwave oven increases the temperature of 0.400 kg of spaghetti by 45.0°C in 120 s. (a) What was the rate of energy absorption by the spaghetti, given that its specific heat is 3.76103J/kg.C ? Assume the spaghetti is perfectly absorbing. (b) Find the average intensity of the microwaves, given that they are absorbed over a circular area 20.0 cm in diameter. (C) What is the peak electric field strength of the microwave? (d) What is its peak magnetic field strength?
Why is t1 radiation pressure of an electromagnetic wave on a perfectly reflecting surface twice as large as the pressure on a perfectly absorbing surface?
Suppose the maximum safe intensity of microwaves for human exposure is taken to be 1,00 W/m2. (a) 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 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 the safe intensity? (Note that early radar units leaked more than modem ones do. This caused identifiable health problems, such as cataracts, for people who worked near them.)
Suppose a spherical particle of mass m and radius R in space absorbs light of intensity I for time t. (a) How much work does the radiation pressure do to accelerate the particle (mm rest In the given tine It absorbs the light? (b) How much energy canted by the electromagnetic waves is absorbed by the particle over this time based on the radiant energy incident on the particle?
Problem 6:An antenna radiates equally in all directions over a half space above a perfectly conductingground plane. The strength of the electric field at 2.2 km from the antenna is 73 dB relativeto one microvolt per meter. Calculate the power radiated and the radiation resistancegiven that the feeding current is 1.2 A (rms)
(a) A center-fed dipole with a z-directed current has electrical length L/A=0.075, show that the current distribution may be assumed to be triangular in form. Then find its directivity and radiation resistance. (b) Draw the current distribution for 1.52 length dipole antenna also find the radiation pattern for this antenna and tell about the HPBW of this antenna. Explain Why the /2 Dipole is the Most Popular antenna Dipole, write your answers by giving at least four different comments.
(a) What is the intensity in W/m2 of a laser beam used to burn away cancerous tissue that, when 90.0% absorbed, puts 500 J of energy into a circular spot 2.00 mm in diameter in 4.00 s?(b) Discuss how this intensity compares to the average intensity of sunlight (about 700 W/m2 ) and the implications that would have if the laser beam entered your eye. Note how your answer depends on the time duration ofthe exposure.
(a) What is the intensity in W/m2 of a laser beam used to burn away cancerous tissue that, when 90.0% absorbed, puts 500 J of energy into a circular spot 2.00 mm in diameter in 4.00 s? (b) Discuss how this intensity compares to the average intensity of sunlight (about 700 W/m2 ) and the implications that would have if the laser beam entered your eye. Note how your answer depends on the time duration of the exposure.
A Styrofoam spherical ball of radius 2 mm and mass20 µg is to be suspended by the radiation pressure in avacuum tube in a lab. How much intensity will be requiredif the light is completely absorbed the ball?
The radiation pressure exerted by the Sun on theEarth counteracts the gravitational attraction and puts theEarth into an orbit that is farther from the Sun than if therewere no radiation pressure. It can be shown that the distanceadded to Earth’s orbital radius is given by 1Frad>Fg2r, where Frad isthe radiation force exerted on Earth by the Sun, Fg is the gravitational force between the Earth and Sun, and r is the average orbital radius. (a) If the intensity of sunlight that strikesEarth is 1360 W>m2, what is Frad, assuming the Earth is a perfect absorber? (b) Assuming r = 1.50 * 1011 m, what is Fg?(c) What is the additional distance added to Earth’s orbital radiusby the radiation pressure?
Assume (unrealistically) that a TV station acts as a point source broadcasting isotropically at 2.5 MW. What is the intensity of the transmitted signal reaching a nearby star that is 44 ly away. (An alien civilization at that distance might be able to watch X Files.) A light-year (ly) is the distance light travels in one year. Number Units Use correct number of significant digits; the tolerance is +/-1 in the 2nd significant digit
The average intensity of the solar radiation that strikes normally on a surface just outside Earth’s atmosphere is 1.4 kW/m2. (a) What radiation pressure pr is exerted on this surface, assuming complete absorption? (b) For comparison, find the ratio of pr to Earth’s sea-level atmospheric pressure, which is 1.0 * 10^5 Pa.

SEE MORE QUESTIONS

Recommended textbooks for you

University Physics Volume 2

Physics

ISBN:

9781938168161

Author:

OpenStax

Publisher:

OpenStax

Glencoe Physics: Principles and Problems, Student…

Physics

ISBN:

9780078807213

Author:

Paul W. Zitzewitz

Publisher:

Glencoe/McGraw-Hill

University Physics Volume 2

Physics

ISBN:

9781938168161

Author:

OpenStax

Publisher:

OpenStax

Glencoe Physics: Principles and Problems, Student…

Physics

ISBN:

9780078807213

Author:

Paul W. Zitzewitz

Publisher:

Glencoe/McGraw-Hill

SEE MORE TEXTBOOKS