1. A spherical lightbulb with a diameter of 3.20cm radiates light equally in
all directions, with a power of 4.50 W.
(a) Find the flux at the surface of the bulb.
(b) Find the flux 7.20 m from the center of the bulb.
(Here the light bulb may be treated as a point source.)
(c) At this 7.20 m distance, a lens is set up with its optical axis
aligned with the bulb. The lens has a circular cross-section with a diameter
of 15.0 cm and a focal length of 35.0 cm. Find the diameter of the image of
the bulb.
(d) Find the flux of the image.
2. Frank D. Drake, an investigator in the SETI (Search for
Extra-Terrestrial Intelligence) program, has said that the Arecibo radio telescope in Puerto Rico, 'can detect a signal which lays down
on the entire surface of the earth a power of only one picowatt.'
The radius of the Earth is 6.37 X 106 m. The diameter of the Arecibo dish is
1000 ft.
(1 picowatt = 10-12 W).
(a) What is the power actually received by the Arecibo dish for such a signal?
(b) What would be the power of a source at the center of our galaxy that
could provide such a signal? The distance to the center of the galaxy is
about 2.2 X 104 light years = 2.2 X 1020m away.
3. The magnitudes of the radii of curvature are 32.5 cm and 42.5 cm for the two faces of a biconcave lens. The glass has index 1.53 for violet light and 1.51 for red light. For a very distant object, locate (a) the image formed by violet light and (b) the image formed by red light. How do the images compare to each other in terms of location and relative size?
4. Supposing that the following object is imaged by a lens system suffering spherical aberration only, make a sketch of the image.
5. Two light pulses are emitted simultaneously from a source. Both pulses tr
avel
to a detector, but one first passes through 6.20 m of ice (n = 1.3).
(a) Determine the optical path difference for the two pulses.
(b) Determine the difference in the pulses' times of arrival at the detector.
(c) Determine the phase difference in radians for the pulses at the detector, in terms of the wavelength or frequency.
6. Does the spacing between fringes in a two-slit interference pattern
increase, decrease, or stay the same if
(a) the slit separation is increased?
(b) the color of the light is switched from red to blue?
(c) the apparatus is submerged in water?
(d) If the slits are illuminated with white light, then at any side
maximum, does the blue component or the red component peak closer to the
central maximum?
7. A double-slit diffraction pattern is formed using mercury green light at 546.1 nm. Each slit has a width of 0.100m. The pattern reveals that the 4th-order interference maxima are mising from the pattern. What is the slit separation?
Last updated February 25, 2005