Question

A typical laser pointer is rated at 5.0 mW. It outputs red light with a wavelength of about 6300 Angstrom. How many photons of laser light will be emitted from the pointer if it is used 120 seconds.
E = hc/wavelength, solve for E in joules.
1 watt = 1 J/s, make the conversion to 5 mW, then see how many joules is needed to run 120 sec. I would then use a proportion to determine how many of the photons are needed.

Related Questions

A helium-neon laser emits light of wavelength 633 nanometers(nm). Light from an argon laser has a wa... Consider the light from a green laser pointer (wavelength = 532 nm). What is the energy of 1 photon... The wavelength of the light of a red laser pointer is 6.35*10 to power of -7 m convert this to nm A laser pointer produces a very narrow laser beam of light. A laser pointer is used to create two mo...