- What was the flux of energy per square cm per second in
Taylor's experiment?
The paper states that this flux is F = 5 x 10^(-6) ergs per square cm per sec 5 x 10^(-13) Joules per square cm per sec

- Assume the light was yellowish, with
wavelength lambda = 550 nm.
What is the energy of each photon, in ergs?
How many photons strike one square cm each second?
The energy of a photon is E = h * nu = (h * c) / lambda = 3.6 x 10^(-19) Joules = 3.6 x 10^(-12) ergs so the number of photons striking one square cm each second must be N = F / E = 1.38 x 10^6 photons per square cm per sec

- Photographic film responds to light because it contains
grains of silver halide. Each grain is roughly 2
micrometers in diameter. How many grains are there in one square cm?
If the grains are assumed to be packed in a simple square grid, then N(top) = number of grains across top of 1 square cm = (1 cm) / (2 x 10^(-6) m) = 5000 N(left) = number of grains across left side of 1 square cm = (1 cm) / (2 x 10^(-6) m) = 5000 N(grains) = (number across top) * (number along left edge) = 5000 * 5000 = 25 x 10^(6)

- How many photons strike a grain each second?
If the N photons hitting each square cm in one second are randomly distributed across the entire square, then the number landing on any particular grain in one second must be N / N(grains) = 1.38 x 10^6 / 25 x 10^6 = 0.055 photons per grain per second

- What is the interval between successive photons striking
a grain in Taylor's experiment?
The average interval between successive photons hitting the same grain is just the reciprocal of the number of photons hitting the grain each second. interval = 1 / (0.055 photons per grain per second) = 18 seconds between photons

Copyright © Michael Richmond. This work is licensed under a Creative Commons License.