Concept explainers
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: A Strategic Approach with Modern Physics (4th Edition)
- Sources A and B emit long-range radio waves of wavelength 380 m, with the phase of the emission from A ahead of that from source B by 90°. The distance rA from A to a detector is greater than the corresponding distance rB from B by 140 m. What is the magnitude of the phase difference at the detector?arrow_forwardSound waves diffract or bend around the edges of a doorway. Larger wavelengths diffract more than smaller wavelengths. (a) The speed of sound is 343 m/s. With what speed would a 57.0 kg person have to move through a doorway to diffract to the same extent as a 146 Hz bass tone? (b) At the speed calculated in part (a), how long in years (365.25 days) would it take the person to move a distance of one meter?arrow_forwardA laser used in LASIK eye surgery produces 55 pulses per second. The wavelength is 220.0 nm (in air), and each pulse lasts 10.0 ps. The average power emitted by the laser is 120.0 mW and the beam diameter is 0.800 mm. How long (in centimeters) is a single pulse of the laser in air?arrow_forward
- answer is D, explain how?arrow_forwardGiven once SpaceX's StarLink can provide global internet by sending light between satellites in space, what is the expected time delay for a Whatsapp call from Indianapolis to London which is about 6416 km apart? In other words, how long does light need to travel between Indianapolis and London? µs = 1 × 10¬°s, ms = 1 × 10¬³s tdelay = 2.14µs tdelay = 2.14ms %3D tdelay = 214µs O tdelay = 2.14s %3Darrow_forwardRadiation from a distant neutron star is found by a satellite far from Earth to have wavelength λ = 3 nm. a) What is the ratio δλ/λ, where δλ is the difference with respect to the measurement by a detector on the surface of the Earth? The Schwarzschild radius of the Earth is 8.7 mm, while its actual radius is 6.4 × 106 m. b) What is the ratio δ′ λ/λ, where δ′ λ is the difference with respect to the wavelength of the same radiation at the time of emission from the neutron star’s surface? Assume that the neutron star’s actual radius is three times its (typically 4 km) Schwarzschild radius.arrow_forward
- Handwrittenarrow_forwardX-rays have a wavelength small enough to image individual atoms, but are challenging to detect because of their typical frequency. Suppose an X-ray camera uses X-rays with a wavelength of 3.10 nm. Calculate the frequency of the X-rays. Be sure your answer has the correct number of significant digits.arrow_forwardOften in optics scientists take advantage of effects that require very high intensity light. To get the desired effect a scientist uses a laser with power P = 0.0015 W to reach an intensity of I = 350 W/cm2 by focusing it through a lens of focal length f = 0.15 m. The beam has a radius of r = 0.0011 m when it enters the lens.Randomized VariablesP = 0.0015 WI = 350 W/cm2f = 0.15 mr = 0.0011 m Part (a) Express the radius of the beam, rp, at the point where it reaches the desired intensity in terms of the given quantities. (In other words, what radius does the beam have to have after passing through the lens in order to have the desired intensity?) Part (b) Give an expression for the tangent of the angle that the edge of the beam exits the lens with with respect to the normal to the lens surface, in terms of r and f? Part (c) Express the distance, D, between the lens's focal point and the illuminated object using tan(α) and rp. Part (d) Find the distance, D, in centimeters.arrow_forward
- Suppose that a detector in the Hubble Space Telescope was capable of detecting visible light in the wavelength range of 400 to 700 nm. (a) List all the wavelengths for the hydrogen atom that are in this range and their series name. (b) The detector measures visible wavelengths of 537.5 nm, 480.1 nm, and 453.4 nm that researchers believe are due to the hydrogen atom. Why are all the known visible hydrogen lines not detected? (c) Use these data to calculate the speed of the stellar object that emitted the spectra. Assume that the object is not rotating. Why might rotation be an issue?arrow_forwardA light ray is incident from air into glass (ng = 1.52) then onto water (ny = 1.33). The wavelength of light in air (na = 1) is hair = 500 nm and it travels at a speed c = 3 x 10% m/s. The wavelength of light, 2, and its frequency, f, in water, are, respectively: 376 nm,8x10*11 Hz 500 nm,6x10*14 Hz 376 nm,6x10*14 Hz 500 nm,8x10*11 Hzarrow_forwardThe absorption cross section for fluorescein, a dye that is used as a fluorescent probe for biological imaging (see the Chapter Opener image), is 9.25 × 10-16 cm2 molecule-1 at 500 nm. How much light is transmitted through a 1-cm path length by a standard 10-6 M solution of fluoresceinused to label biological samples?arrow_forward
- College PhysicsPhysicsISBN:9781285737027Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningPhysics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning