Question

Electromagnetic radiation with a wavelength of 725 nm appears as red light to the human eye. The energy of one photon of this light is 2.74 × 10-19 J. Thus, a laser that emits 1.3 ×10-2 J of energy in a pulse of light at this wavelength produces ________ photons in each pulse.

Answer 1

Answer:

4.7 × 10¹⁶ photons

Explanation:

Step 1: Given data

• Wavelength of the laser: 725 nm

• Energy in a pulse of light: 1.3 × 10⁻² J

• Energy per photon of this light: 2.74 × 10⁻¹⁹ J/photon

Step 2: Calculate the number of photons in each pulse

We can calculate the number of photons in each pulse by dividing the energy in a pulse of light by the energy per photon of this light.

1.3 × 10⁻² J / (2.74 × 10⁻¹⁹ J/photon) = 4.7 × 10¹⁶ photon