Question

PHYS-1200/1250 Lab Manual Name Section 38A - Photons 1) Write Einstein's relationship between the energy of a photon and the frequency of the electromagnetic wave that characterizes the photon beam, Explain in words what cach term represents. Words Relationship Ehf histhu pian constant is the wayicha 2) What is the approximate frequency, energy, and wavelength (in meters) of a green light photon in the middle of the visible spectrum? Frequency(Hz) _Energy (Joules): 3-54X10 Energy (eV): Wavelength: 3) A beam of light has total power of 0.10 Watt. How many photons per second of wavelength 320 nm are needed to carry this power? na Pt2 nc = 60.10)(1)(520x10-9m) _photons/s (6.63*10-345.6) (3x 108 mis) 4) The flux per area of visible photons per second from the Sun arriving at the surface of the Earth is about 3x102' m's!. Assuming the average wavelength of visible photons from the Sun is 600 nm, estimate the intensity of sunlight in Watts/m”. go _W.m 5) Light of wavelength 400 nm is incident on a surface with intensity of 0.5 W/m. The wavelength of the light is increased to 700 nm while maintaining the same intensity. Does the flux per area (photons/mºs) increase, decrease, or remain the same? Explain. 149

Answer 1

ege 1. Eur E = energy h= plank constant 2 = frequency Green ling Frequency 566THt; Energy = 2.3401.67 Energy - 2.34ev; wavelength =(495-570) x 10 m no of photon (n) n- Ptd ne - 2x107 P = power - 0.10 watt t=1s; d = no soum h = 6.63x1024 / ; e = 3x10 m/s 14 dne - I I =992 watts/mit I = intensity of sunlight = 3x1021 m 2 x = 6oonm=600x100m 5. p = flux Per area if intensity is constant pad as & increased; so flux Per area increases.