What is the number of photons of light with a wavelength of 4000 pm that provide 1 J of energy?

Hint: Energy of light is inversely proportional to the wavelength.
Formula: The energy of one photon = hc/λ
Here, c is the velocity of light, λ is wavelength and h is Plank's constant.
Step 1: To find the energy of one photon.
Given that,
The wavelength of light = 4000 pm or 4000 × 10⁻¹² m or 4 × 10⁻⁹ m.
The energy of one photon = hc/λ = (6.626 × 10⁻³⁴ × 3 × 10⁸) / (4 × 10⁻⁹) = 4.97 × 10⁻¹⁹ J.
Step 2: To find the number of photons that provide 1 J of energy.
The number of photons that will provide 1 J of energy is 1 / (4.97 × 10⁻¹⁹ J) = 2.01 × 10¹⁸ J.
Final answer: 2.01 × 10¹⁸