Light of wavelength 2000 Å falls on a metallic surface whose work function is 4.21 eV. Calculate the stopping potential

Explanation

To solve the problem step by step, we will follow the outlined procedure:

**Step 1: Convert the wavelength from angstroms to meters.**
- Given wavelength, \( \lambda = 2000 \, \text{Å} = 2000 \times 10^{-10} \, \text{m} = 2.0 \times 10^{-7} \, \text{m} \).

**Step 2: Calculate the energy of the incident photon using the formula \( E = \frac{hc}{\lambda} \).**
- Here, \( h = 6.63 \times 10^{-34} \, \text{Js} \) (Planck's constant),
- \( c = 3 \times 10^8 \, \text{m/s} \) (speed of light),
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