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Unformatted text preview: 1271 Chapter 33 1. Since , we find f is equal to 8 9 9 2 9 2 (3.0 10 m/s)(0.0100 10 m) 7.49 10 Hz. (632.8 10 m) c c 2. (a) The frequency of the radiation is f c 30 10 10 10 6 4 10 4 7 10 8 5 6 3 . ( . )( . . m / s m) Hz. (b) The period of the radiation is T f 1 1 4 7 10 212 3 32 3 . min Hz s s. 3. (a) From Fig. 332 we find the smaller wavelength in question to be about 515 nm. (b) Similarly, the larger wavelength is approximately 610 nm. (c) From Fig. 332 the wavelength at which the eye is most sensitive is about 555 nm. (d) Using the result in (c), we have 8 14 3.00 10 m/s 5.41 10 Hz 555 nm c f . (e) The period is T = 1/ f = (5.41 10 14 Hz) –1 = 1.85 10 –15 s. 4. In air, light travels at roughly c = 3.0 10 8 m/s. Therefore, for t = 1.0 ns, we have a distance of d ct ( . . 30 10 0 30 8 9 m / s) (1.0 10 s) m. 5. If f is the frequency and is the wavelength of an electromagnetic wave, then f = c . The frequency is the same as the frequency of oscillation of the current in the LC circuit of the generator. That is, f LC 1 2 / , where C is the capacitance and L is the inductance. Thus CHAPTER 33 1272 2 LC c . The solution for L is 2 9 2 21 2 2 2 2 12 8 550 10 m 5.00 10 H. 4 4 17 10 F 2.998 10 m/s L Cc This is exceedingly small. 6. The emitted wavelength is c f 2 c LC 2 2.998 10 8 m/s 0.253 10 6 H 30.0 10 12 F 5.19 m. 7. The intensity is the average of the Poynting vector: I S avg cB m 2 2 3.0 10 8 m/s 1.0 10 4 T 2 2 1.26 10 6 H/m 2 1.2 10 6 W/m 2 . 8. The intensity of the signal at Proxima Centauri is I P 4 r 2 3.0 10 6 W 4 4.3ly 9.46 10 15 m/ly 2 1.4 10 28 W/m 2 . 9. If P is the power and t is the time interval of one pulse, then the energy in a pulse is E P t 100 10 12 W 1.0 10 9 s 1.0 10 5 J. 10. The amplitude of the magnetic field in the wave is B m E m c 1.80 10 4 V/m 2.998 10 8 m/s 6.00 10 13 T. 11. (a) The amplitude of the magnetic field is 9 9 8 2.0V/m 6.67 10 T 6.7 10 T. 2.998 10 m/s m m E B c 1273 (b) Since thewave E oscillates in the z direction and travels in the x direction, we have B x = B z = 0. So, the oscillation of the magnetic field is parallel to the y axis....
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This document was uploaded on 04/22/2011.
 Spring '11
 Radiation

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