-
The work function of a surface of a photosensitive material is 6.2 eV. The wavelength of incident radiation for which the stopping potential is 5 V lies in the:
-
- Ultraviolet region
- Visible region
- Infrared region
- X-ray region
Correct Option: A
Work function, φ0 = 6.2eV.
Stopping potential V0 = 5V.
As, eV0 = hv – φ0
| or eV0 + φ0 = | λ |
| or λ = | eV0 + φ0 |
| λ = | 1.6 × 10-19 × 5J + 6.2 × 1.6 × 10-19J |
| λ = | m | 1.6 × 10-19 (5 + 6.2) |
| = | 1.10 × 10-7 m | 17.92 × 10-19 |
Thus the wavelength of the incident radiation lies in the ultraviolet region.
