Question

A laser with a power output of 2.00 mW at a wavelength of 400 nm is projected onto calcium metal. How many electrons per second are ejected?

a)2.50 x 10^15 electrons/s
b)5.00 x 10^15 electrons/s
c)7.50 x 10^15 electrons/s
d)1.00 x 10^16 electrons/s

Answer 1

The question involves the photoelectric effect, where electrons are emitted from a material when it is exposed to light. To determine how many electrons per second are ejected, calculate the energy of each photon and divide the laser's power output by that energy.

Step-by-step explanation:

The question asks about the photoelectric effect, which occurs when light is shone onto a material, causing it to emit electrons. To find out how many electrons per second are ejected (photoelectrons), we need to calculate the energy of each photon using the formula E = hc/λ, where h is Planck's constant (6.626 x 10^-34 J·s), c is the speed of light (3.00 x 10^8 m/s), and λ is the wavelength of the light (400 nm or 400 x 10^-9 m).

Once we have the energy per photon, we can determine how many photons are emitted per second by the laser by dividing the power output of the laser by the energy per photon. From there, assuming each photon results in the ejection of one electron, we can calculate the number of electrons ejected per second.