Absorption & Emission of Light Stimulated Absorption & Emission‚ Spontaneous Emission E2 Incident radiation hν hν Emitted & transmitted radiation E1 Resonance condition E2-E1=hν • Rate of stimulated emission is: −dN1/dt = N1B1->2 ρ(ν) • Rate of absorption is the sum of the rated due to stimulated emission and spontaneous emission: −dN2/dt = N2B2->1 ρ(ν) + N2A2->1 where B1->2 is the Einstein transition probability for induced absorption‚ B2->1 is the Einstein transition probability
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awareness of the nature of light in our daily life; and B. answer three out of five items correctly. II. SUBJECT MATTER: A. Unit: Electricity Chapter: Interaction of Electric Charges Topic: Nature of Light 1. Concepts: • Light is an electromagnetic wave‚ a form of energy that can travel freely across space. The speed of light is 3.0X108 m/s. • Luminous objects became visible because of the light they emitted while illuminated objects do not emit light but they are capable of reflecting
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Sound and music are parts of our everyday sensory experience. Just as humans have eyes for the detection of light and color‚ so we are equipped with ears for the detection of sound. We seldom take the time to ponder the characteristics and behaviors of sound and the mechanisms by which sounds are produced‚ propagated‚ and detected. The basis for an understanding of sound‚ music and hearing is the physics of waves. Sound is a wave which is created by vibrating objects and propagated through a medium
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in communication Name and define the functions of various standard organizations locally and internationally • • • This chapter from (Goleniewski and Jarrett‚ 2006) discusses the types of transmission lines and network connections‚ the electromagnetic spectrum‚ and what bandwidth is all about in the emerging broadband era. It looks at the differences between analog and digital signals. Finally‚ this chapter describes the various standards bodies and their roles in shaping aspects of 2.1
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MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Electrical Engineering and Computer Science Problem Set No. 2 6.632 Electromagnetic Wave Theory Issued: 02/15/07 R Spring Term 2007 Due: 02/22/07 R -----------------------------------------------------------------------------Reading assignment: Section 3.2 J. A. Kong‚ “Electromagnetic Wave Theory” Problem P2.1 (a) The complex permittivity for bottom round steak is about = 40(1 + i0.3) o at the operating frequency (2.5 GHz) of a microwave oven. What
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3B Wave Motion II 5 Chapter 5 Nature of Waves Practice 5.1 (p. 7) 1 B 2 D 3 (a) Transverse wave 11 Speed = f = 5 0.2 = 1 m s1 1 1 (ii) Period = = = 0.2 s f 5 (a) (i) (b) A heavier string (length unchanged) has greater mass per unit length. Therefore‚ (b) Longitudinal wave 4 (a) Water wave and EM wave (b) Sound wave 5 12 For case I‚ energy is transferred to the cork directly from the stone. For case II‚ energy is transferred to the cork through water waves. 6 = 1.6667 = 1
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to their family. Many teenagers who use the computers don’t seem realize that sitting in front of the computer is harmful at all. The electromagnetic waves from the computer-screen make our brain cells get stiffen every second. Human eyes can also lose its focus and get dehydrated easily because the ELF‚ VLF‚ RF and MICROWAVE (types of injurious electromagnetic waves). These harmful waves can cause headache‚ drop in eyesight‚ a brain tumor and leucosis in the worst case. Moreover‚ sitting in front
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information Ex. Radio wave When the motion of the particles is perpendicular to the motion of the wave‚ it is called a traverse wave Pointing down Acceleration down Wave -> We see the motion of the medium Soundwaves -> air Lightwaves = electromagnetic waves Stadium waves -> people Water waves -> water Light waves -> no medium Pointing up Acceleration up Without tension‚ there can be no traverse waves in a medium. -> Do not occur inside liquids and gases -> can occur on surface of
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something about the wavelengths that make up a particular type of radiation (i.e.‚ the spectrum of radiation)‚ one could use an object such as simple diffraction parallel-slit grating in the form of a spectrometer. For example‚ molecules‚ atoms‚ and nuclei typically radiate or scatter radiation that corresponds to discrete frequencies and hence discrete wavelengths‚ λ. Knowing the spectrum (the intensity and wavelengths) of these radiations can tell us a lot about the molecule‚ atom‚ and nucleus under
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Waves transfer _energy_ from place to place‚ and it spreads _out evenly_ from the source. 11. What is a mechanical wave? _A wave that requires a medium to travel through._ Example of a mechanical wave? _Sound_ An example of a non-mechanical wave (electromagnetic)? _Light_ 12. Label the following parts on a longitudinal wave: Compression a. Compression b. Rarefaction 13. In a longitudinal wave‚ the particles move Rarefaction parallel / perpendicular to the direction which the energy moves. 14. A longitudinal
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