How Many Photons per Second Does a Laser Emit?

How many photons per second does a laser emit if it emits a light beam with a power of 4.1 mW and a wavelength of 633 nm?

Calculating the Number of Photons Emitted per Second

To calculate the number of photons emitted per second by the laser, we need to determine the energy of a single photon and then divide the total power emitted by the energy of each photon. The energy (E) of a photon can be calculated using the equation: E = hc / λ Where: E is the energy of the photon, h is Planck's constant (approximately 6.626 x 10^-34 J·s), c is the speed of light in vacuum (approximately 3.0 x 10^8 m/s), and λ is the wavelength of the light. Let's calculate the energy of a single photon: E = (6.626 x 10^-34 J·s * 3.0 x 10^8 m/s) / (633 x 10^-9 m) E ≈ 3.135 x 10^-19 J Now, we can calculate the number of photons per second by dividing the total power emitted by the energy of each photon: Number of photons per second = Total power emitted / Energy per photon Total power emitted = 4.1 mW = 4.1 x 10^-3 W Number of photons per second = (4.1 x 10^-3 W) / (3.135 x 10^-19 J) Number of photons per second ≈ 1.31 x 10^16 photons/s Therefore, this laser emits approximately 1.31 x 10^16 photons per second.

← The bright stars rigel and betelgeuse Projectile motion and free fall worksheet exploring physics concepts in a fun way →