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Test 1 material

# Test 1 material - Chapter 1 Sources of light o Stars and...

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1-15-08: Chapter 1 Sources of light o Stars and sun, not moon (reflection of sun) Waves o Rope o Ocean o Sound o Shock Amplitude o Changes wave height Frequency o Changes # of waves o 1/ Time o F increases, distance between crests gets shorter Damping o How long/strong wave lasts Wave moves left and right o Rope moves up and down Air carries sound o Light doesn’t need air to carry waves (no medium needed) Waves need medium to move (sound) o Sound is very slow in speed Waves that do not need medium to move them are electromagnetic waves Periodic waves o Distance between wavelength Aperiodic waves o Doesn’t repeat itself 10 cycles/second Time (t)= 1/10 cycle / second (always the inverse) Period= Time=T= 1/frequency o Measuring the time taken for a wavelength to pass a give point, crest to crest Light o Very fast in speed Speed o Distance/time= wavelength/time= wavelength * frequency 1-17-08: Chapter 1 C= 3*10^8 m/s and d= 1/3 m o Calculate o 1/3*(3*10^8)= 10^-9 seconds nanosecond We cannot see most of the light on the electromagnetic spectrum o Visible light is between 10^-6 & 10^-7 o Longer wavelength is infrared

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o Shorter wavelength is * Wavelength of red light o 650 nm= 650 * 10^-9 m o .650 um= .650 * 10^-6 m Radio frequency is 101.5 MHz o AM has longer wavelength that FM radio o Wavelength is c/f= cT o (3* 10^8 m/s) / (101.5 * 10^6/s) = 3 meters 1-22-08 Visible light o Between 700 nm (infrared, less energetic, less waves) – 400 nm (ultraviolet, more energetic, more waves) Generate a wave on a rope o Raise and lower one end quickly Light waves o Disturbances in the electromagnetic field , a nonmaterial physical entity whose equilibrium state is vacuum Electromagnetic wave o A propagating loop of field lines o Coupled electric and magnetic fields o Sources of electromagnetic waves Heat Oscillating electric field due to current changes Electrons in an excited atom Neon sign, fluorescent light Chemical excitation Firefly, phosphorescence Amplitude, wavelength, frequency define direction, energy, and intensity of the radiation Generating electromagnetic waves o Source Mechanism Radio stations voltage in a circuit Microwave voltage in a circuit Human body heat/ neural activity Cell phone voltage in a circuit Neon light excited atoms Laser excited atoms Warm stove
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Test 1 material - Chapter 1 Sources of light o Stars and...

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