Ch10_appendix_A

Ch10_appendix_A - Appendix A Electromagnetic radiation A.1...

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Appendix A Electromagnetic radiation A.1 Electromagnetic radiation ( 電磁輻射 ) When the velocities of moving electric charges are changed, electromagnetic fields ( 電磁場 ) are generated. oscillations of electric and magnetic fields propagate in space electromagnetic waves ( 電磁波 ) (EM waves) carry energy e.g. visible light is a kind of electromagnetic waves Fig. A-1 All electromagnetic waves travel at the speed of light. The wavelength is the distance between successive peaks, and the frequency is the number of peaks that passes us in one second. Characteristics of electromagnetic waves Wavelength ( 波長 ): Spatial separation between successive peaks of a continuous wave train. Frequency ( 頻率 ): Number of complete waves (peaks) pass a given position per second (Fig. A-1) Speed of electromagnetic waves = speed of light 3 × 10 8 m/s is a constant in vacuum , independent of wavelength and frequency.
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This note was uploaded on 04/03/2011 for the course PHYSICS 101 taught by Professor Tiu during the Spring '11 term at HKU.

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Ch10_appendix_A - Appendix A Electromagnetic radiation A.1...

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