ch33 - 1271 Chapter 33 1 Since we find f is equal to 8 9 9...

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. 33-2 we find the smaller wavelength in question to be about 515 nm. (b) Similarly, the larger wavelength is approximately 610 nm. (c) From Fig. 33-2 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 the-wave 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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