The U.S. Food and Drug Administration limits the radiation leakage of microwave ovens to no more than 5.0 mW/cm2 at a distance of 2.0 in. A typical cell phone, which also transmits microwaves, has a peak output power of about 2.0 W. (a) Approximating the cell phone as a point source, calculate the radiation intensity of a cell phone at a distance of 2.0 in. How does the answer compare with the maximum allowable microwave oven leakage? (b) The distance from your ear to your brain is about 2 in. What would the radiation intensity in your brain be if you used a Bluetooth headset, keeping the phone in your pocket, 1.0 m away from your brain? Most headsets are so-called Class 2 devices with a maximum output power of 2.5 mW.

The AM radio band in a particular area has a frequency range of 554 kHz to 1620 kHz. How long is the wavelength of the radiation at the beginning of the range and how long is the wavelength of the radiation at the end of the range? Answer in units of m.

What is the radiation pressure 1.2 m away from a 600 W lightbulb? Assume that the surface on which the pressure is exerted faces the bulb and is perfectly absorbing and that the bulb radiates uniformly in all directions. Number Units Use correct number of significant digits; the tolerance is +/-1 in the 2nd significant digit

Solar radiation reaches Earth at a rate of about 1,400 W/m2. If all this energy were absorbed, what would be the average force exerted by radiation pressure on a square meter oriented at right angles to the sunlight?

(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 2.3 mm in diameter in 3 s? 2 W/m (b) Reflect on how this intensity compares to the average intensity of sunlight (about 1W/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. The intensity of a laser is abc lasers can be very damaging 100 1,000 10E7 - 10E8 10E12 times that of the sun, so clearly

Item 14 The radiation pressure exerted by the Sun on the Earth counteracts the gravitational attraction and puts the Earth into an orbit that is farther from the Sun than if there were no radiation pressure. It can be shown that the distance added to Earth's orbital radius is given by (Frad/Fg)r, where Frad is the radiation force exerted on Earth by the Sun, F, is the gravitational force between the Earth and Sun, and r is the average orbital radius. Part A If the intensity of sunlight that strikes Earth is 1240 W/m², what is Frad, assuming the Earth is a perfect absorber? Express your answer to three significant figures and include appropriate units. Value Submit Part B O Value Assuming r = 1.50 × 10¹¹ m, what is F? Express your answer to three significant figures and include appropriate units. Submit Part C O Units Request Answer Value Submit μA Units Request Answer What is the additional distance added to Earth's orbital radius by the radiation pressure? Express your answer to three…

Consider a bright star in our night sky. Assume its distance from Earth is 84.9 light-years (ly) and its power output is 4.00 × 1028 W, about 100 times that of the Sun. One light-year is the distance traveled by light through a vacuum in one year. (a) Find the intensity of the starlight at the Earth. W/m² (b) Find the power of the starlight the Earth intercepts. (The radius of Earth is 6.38 x 106 m.) MW

A 1.00-m² solar panel on a satellite that keeps the panel oriented perpendicular to radiation arriving from the Sun absorbs 1.40 kJ of energy every second. The satellite is located at 1.00 AU from the Sun. (The Earth-Sun distance is approximately 1.00 AU.) How long would it take an identical panel that is also oriented perpendicular to the incoming radiation to absorb the same amount of energy, if it were on an interplanetary exploration vehicle 2.85 AU from the Sun? S

Estimate the radiation pressure due to a 75 W bulb at a distance of 7.8 cm from the center of the bulb. Express your answer to two significant figures and include the appropriate units. ? Prad = Value Units Estimate the force exerted on your fingertip if you place it at this point. Assume that the area of a fingertip is 1.3 cm? Express your answer to two significant figures and include the appropriate units. | ? F = Value Units

When light reaches the surface of a perfect absorber, it gives up its linear momentum. to the surface. The radiation pressure P (average force per unit area) is given by: P = I/c0 , where I is the intensity of light and c0 is the speed of light in free space. In a perfect reflector the pressure exerted by light is twice that exerted by it on a perfect absorber, because linear momentum changes direction, rather than simply being absorbed. The intensity of sunlight reaching the earth is about 1300 W/m2. a) If sunlight hits a perfect absorber, what pressure does the light exert on the absorber? b) What pressure does light exert on a perfect reflector? c) To what fraction of atmospheric pressure corresponds the pressure exerted by light on a perfect reflector?