PHYS 1061 Lecture Notes - Lecture 32: Habitat, Thermal Velocity, Starry Sky
Document Summary
Lecture - 32: let"s start with photon energy, light is quantized into packets called photons, photons have associated: Energy: e = h(cid:1: higher frequency photons (cid:1) higher energy (cid:1) more damaging. Momentum: p = h(cid:1)/c: the constant, h, is planck"s constant. Has tiny value of: h = 6. 63(cid:1)10-34 j s: how come i"ve never seen a photon, sunny day (outdoors): 1015 photons per second enter eye (2 mm pupil: moonlit night (outdoors): 5 1010 photons/sec (6 mm pupil: moonless night (clear, starry sky) 108 photons/sec (6 mm pupil: light from dimmest naked eye star (mag 6. 5): Integration time of eye is about 1/8 sec 100 photon threshold signal level: quantum wavelength, every particle or system of particles can be defined in quantum mechanical terms. And therefore have wave-like properties (p is momentum: the quantum wavelength of an object is: (cid:1) 10-34 meters (too small to matter in macro environment!!: typical quantum objects:
