The space between two hollow concentric spheres of radii 25m and 45m is under vacuum. Exchange of radiation occurs only between the outer surface (S1) of the small sphere and inner surface (S2) of the larger sphere. The fraction of radiation leaving S2 and reaches Si is a) 0.308 b) 0.41 c) 0.52 d) 0.61

Large quantities of dust should have been left behind after the creation of the solar system. Larger dust particles, comparable in size to soot and sand grains, are common. They create shooting stars when they collide with the earth's atmosphere. But very small dust particles are conspicuously absent. Astronomers believe that the very small dust particles have been blown out of the solar system by the sun. By comparing the forces on dust particles, determine the diameter of the smallest dust particles that can remain in the solar system over long periods of time. Assume that the dust particles are spherical, black, and have a density of 2000kg/m^3. The sun emits electromagnetic radiation with a power of 3.9×10^26W.

Multiple-Concept Example 6 explores the approach taken in problems such as this one. Quasars are believed to be the nuclei of galaxies in the early stages of their formation. Suppose a quasar radiates electromagnetic energy at the rate of 1.5 × 104¹ W. At what rate (in kg/s) is the quasar losing mass as a result of this radiation? Number i A quasar at the center of a spiral galaxy Units

Assuming the energy density of the cosmic background radiation of the Big Bang has the value 3.75 ✕ 10−14 J/m3, what is the corresponding electric field amplitude (in mV/m)?

A rectangular metal plate measures 0.24 m long and 0.7 m wide. The plate is heated to a temperature of 1,533 K by passing a current through it. Assuming that it behaves like a blackbody, how much power does the plate radiate under these conditions?

Optical tweezers use light from a laser to move single atoms and molecules around. Suppose the intensity of light from the tweezers is 1000 W/m², the same as the intensity of sunlight at the surface of the Earth. (a) What is the pressure on an atom if light from the tweezers is totally absorbed? Pa -27 -29 (b) If this pressure were exerted on a tritium atom, what would be its acceleration? (The mass of a tritium atom is 5.01 x 10- kg. Assume the cross-sectional area of the laser beam is 6.65 x 10- m/s² m².)

What is the magnitude and direction of electric field for the capacitor below? 150 V OV 3.0 mm 1 I 1 1 1.0 mm 1.0 mm k 1.0 mm

A UV lamp used to disinfect objects emits radiation with an rms electric field strength of 65 N/C. Calculate the energy absorbed by a circular target of radius 2 cm that is placed under the lamp for 231 seconds.(Give your answer in joules but don't include the units.)