Police radar detects the speed of a car (Fig. P38.15) as fol- lows. Microwaves of a precisely known frequency are broad- cast toward the car. The moving car reflects the microwaves with a Doppler shift. The reflected waves are received and combined with an attenuated version of the transmitted wave. Beats occur between the two microwave signals. The beat frequency is measured. (a) For an electromagnetic wave reflected back to its source from a mirror approaching at speed 2, show that the reflected wave has frequency :+ v where fis the source frequency. (b) Noting that v is much less than c, show that the beat frequency can be written as feat 2v/A. (c) What beat frequency is measured for a car speed of 30.0 m/s if the microwaves have frequency 10.0 GHz? (d) If the beat frequency measurement in part (c) is accurate to +5.0 Hz, how accurate is the speed measurement? %3D SPEED LIMIT 25 YOUR SPEED Figure P38.15 Bbe Bueg o

Police radar detects the speed of a car (Fig. P38.15) as fol- lows. Microwaves of a precisely known frequency are broad- cast toward the car. The moving car reflects the microwaves with a Doppler shift. The reflected waves are received and combined with an attenuated version of the transmitted wave. Beats occur between the two microwave signals. The beat frequency is measured. (a) For an electromagnetic wave reflected back to its source from a mirror approaching at speed 2, show that the reflected wave has frequency :+ v where fis the source frequency. (b) Noting that v is much less than c, show that the beat frequency can be written as feat 2v/A. (c) What beat frequency is measured for a car speed of 30.0 m/s if the microwaves have frequency 10.0 GHz? (d) If the beat frequency measurement in part (c) is accurate to +5.0 Hz, how accurate is the speed measurement? %3D SPEED LIMIT 25 YOUR SPEED Figure P38.15 Bbe Bueg o

College Physics

11th Edition

ISBN:9781305952300

Author:Raymond A. Serway, Chris Vuille

Publisher:Raymond A. Serway, Chris Vuille

Chapter1: Units, Trigonometry. And Vectors

Section: Chapter Questions

Problem 1CQ: Estimate the order of magnitude of the length, in meters, of each of the following; (a) a mouse, (b)...

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