Problem 57P
A stationary electric dipole is situated at the origin. A positive point charge q (mass m) executes circular motion (radius s) at constant speed in the field of the dipole. Characterize the plane of the orbit. Find the speed, angular momentum and total energy of the charge.29
Tuesday, January 23, 2018 Light: The Cosmic Messenger ASTR 203 - Light • A disturbance in the electromagnetic force thru which energy is transported • Dual Natures - Light as a wave fλ=c - Light as a particle E=hf photon • Light as a Wave - A wave is a pattern which is revealed by its interaction w/ particles • Wavelength: distance between adjacent crests • Amplitude: height of crest, how far crest is from the middle • Frequency: # of crests that pass thru a point each second. Measured in hertz (Hz) - All light travels w/ speed c=300,000 km/s - For a wave, its speed: s= fλ - Speed of light is a constant, c - For light: fλ=c - The higher f is, the smaller λ is, & vice versa - Our eyes recognize f (or λ) as color • Light as a Particle - Light can also be treated as photons - packets of energy - Energy carried by each photon depends on its frequency (color) • E = hf = hc / λ - Bluer light carries more energy per photon 1 Tuesday, January 23, 2018 • The Electromagnetic Spectrum - Short wavelength to Long wavelengths: Gamma, X-Rays, Ultraviolet, Visible, Infrared, Radio • Earth’s Atmosphere allows only certain wavelengths to pass through • Light as Information Bearer - We can separate light into its different wavelengths (spectrum) - By studying the spectrum of a star, we can learn its: • Temperature • Velocity • Composition • Rules for Emission by Opa
