The solar energy flux at Earth's surface is 1.388 × 10³ W m⁻². Assuming average photon wavelength 550 nm, the photon flux is x × 10²¹ photons s⁻¹ m⁻². Find x.
Physics · Photoelectric effect and dual nature of matter
JEE Mains Practice

Question

The solar energy flux at Earth's surface is 1.388 × 10³ W m⁻². Assuming average photon wavelength 550 nm, the photon flux is x × 10²¹ photons s⁻¹ m⁻². Find x.

G1 Physics · Accepted Answer

Step 1: Photon energy is hc/λ. Step 2: Photon flux = power flux divided by photon energy = (1.388×10³)(550×10⁻⁹)/(hc) ≈ 4×10²¹ m⁻² s⁻¹. Thus x=4.