Monochromatic light of wavelength 667 nm is produced by a helium neon laser

Monochromatic light of wavelength 667 nm is produced by a helium neon laser. The power emitted is 9 mW. The number of photons arriving per second on the average at a large irradiated by this beam is:

Options

(a) 3 x 10¹⁶
(b) 9 x 10¹⁵
(c) 3 x 10¹⁹
(d) 9 x 10¹⁷

Correct Answer:

3 x 10¹⁶

Explanation:

λ = 667 x 10⁻⁹ m, P = 9 x 10⁻³ W
P = Nhc / λ, N = no. of photons emitted/sec.
N = (9 x 10⁻³ x 667 x 10⁻⁹) / (6.6 x 10⁻³⁴ x 3 x 10⁸)
= 9 x 6.67 x 10⁻¹⁰ / 3 x 6.6 x 10⁻²⁶
3 x 10¹⁶ / sec

admin:

Related Questions

  1. A tuning fork frequency 512 Hz is vibrated with a sonometer wire and 6 beats per second
  2. The angular speed of earth, so that the object on equator may appear weightless
  3. In thermodynamics processes which of the following statements is not true?
  4. During an adiabatic process, the pressure of a gas is found to be proportional
  5. Cohesive force is experienced between