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Scientists use laser range-finding to measure the distance to the moon with great accuracy. A brief laser pulse is fired at the moon, then the time interval is measured until the “echo” is seen by a telescope. A laser beam spreads out as it travels because it diffracts through a circular exit as il leaves the laser. In order for
the reflected light to be bright enough to detect, the laser spot on the moon must be no more than 1.0 km in diameter. Staying within this diameter is accomplished by using a special large-diameter laser. If
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Physics For Scientists And Engineers
- The movable mirror of a Michelson interferometer is attached to one end of a thin metal rod of length 23.3 mm. The other end of the rod is anchored so it does not move. As the temperature of the rod changes from 15°C to 25 C , a change of 14 fringes is observed. The light source is a He Ne laser, =632.8 nm . What is the change in length of the metal bar, and what is its thermal expansion coefficient?arrow_forwardRadio telescopes are telescopes used for the detection of radio emission from space. Because radio waves have much longer wavelengths than visible light, the diameter of a radio telescope must be very large to provide good resolution. For example, the radio telescope in Penticton, BC in Canada, has a diameter of 26 m and can be operated at frequencies as high as 6.6 GHz. (a) What is the wavelength corresponding to this frequency? (b) What is the angular separation of two radio sources that can be resolved by this telescope? (c) Compare the telescope’s resolution with the angular size of the moon.arrow_forwardTwo radio antennas separated by d = 3.00 102 cm. as shown in Figure P24.7, simultaneously broadcast identical signals at the same the signals. (a) If the car is at the position of the second maximum wavelength. A car travels due north along a straight line at position x = 1.00 103 m from the center point between the antennas and its radio receives the signal. (a) If the car is at the position of the second maximum after that at point O when it has traveled a distance of y = 4.00 102 m northward, what is the wavelength of the signals? (b) How much farther must the car travel from thus position to encounter the next minimum in reception? Hint: Do not use the small-angle approximation in this problem.arrow_forward
- Astronomers observe the chromosphere of the Sun with a filter that passes the red hydrogen spectral line of wavelength 656.3 nm, called the H line. The filter consists of a transparent dielectric of thickness d held between two partially aluminized glass plates. The filter is held at a constant temperature. (a) Find the minimum value of d that produces maximum transmission of perpendicular H light if the dielectric has an index of refraction of 1.378. (b) What If? If the temperature of the filter increases above the normal value, increasing its thickness, what happens to the transmitted wavelength? (c) The dielectric will also pass what near-visible wavelength? One of the glass plates is colored red to absorb this light.arrow_forwardA light ray of wavelength 461.9 nm emerges from a 2-mm circular aperture of a krypton ion laser. Due to diffraction, the beam expands as it moves out. How large is the central bright spot at (a) 1 m, (b) 1 km, (c) 1000 km, and (d) at the surface of the moon at a distance of 400,000 km from Earth.arrow_forwardAs a single crystal is rotated in an x-ray spectrometer (Fig. 3.22a), many parallel planes of atoms besides AA and BB produce strong diffracted beams. Two such planes are shown in Figure P3.38. (a) Determine geometrically the interplanar spacings d1 and d2 in terms of d0. (b) Find the angles (with respect to the surface plane AA) of the n = 1, 2, and 3 intensity maxima from planes with spacing d1. Let = 0.626 and d0 = 4.00 . Note that a given crystal structure (for example, cubic) has interplanar spacings with characteristic ratios, which produce characteristic diffraction patterns. In this way, measurement of the angular position of diffracted x-rays may be used to infer the crystal structure. Figure P3.38 Atomic planes in a cubic lattice.arrow_forward
- The radar system of a navy cruiser transmits at a wavelength of 1.6 cm, from a circular antenna with a diameter of 2.3 m. At a range of 6.2 km, what is the smallest distance that two speedboats can be from each other and still be resolved as two separate objects by the radar system?arrow_forwardA He-Ne gas laser which produces monochromatic light of a known wavelength ? =6.35 ? 10^−7 m is used to calibrate a reflection grating in a spectroscope. The first-order diffraction line is found at an angle of 22 degrees to the incident beam. How many lines per meter are there on the grating?arrow_forwardLight of wavelength 500 nm, near the center of the visible spectrum, enters a human eye. Although pupil diameter varies from person to person, let’s estimate a daytime diameter of 2 mm.(A) Estimate the limiting angle of resolution for this eye, assuming its resolution is limited only by diffraction.arrow_forward
- Astronomers observe the chromosphere of the Sun with a filter that passes the red hydrogen spectral line of wavelength 656.3 nm, called the Hα line. The filter consists of a transparent dielectric of thickness d held between two partially aluminized glass plates. The filter is kept at a constant temperature. (a) Find the minimum value of dα light if the dielectric has an index of refraction of 1.378. (b) If the temperature of the filter increases above the normal value increasing its thickness, what happens to the transmitted wavelength? (c) The dielectric will also pass what near-visible wavelength? One of the glass plates is colored red to absorb this light.arrow_forwardThere is a microscope that uses a wavelength of 470 nm and is designed to resolve objects of size 8,373 nm (which is defined by the Rayleigh criterion) and uses an objective lens with a diameter that is 3.90 mm. In mm, what's the max distance between the objective lens and the object that is being magnified?arrow_forwardbirds of prey have keen eyesight. If the pupil of an eagle has diameter of 10mm, at what altitude could it fly and still see clearley a mouse 7cm long? consider wavelength=550nm.arrow_forward
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