MCQ
When radiation of wavelength $\lambda$ is incident on a metallic surface, the stopping potential is $4.8$ volts. If the same surface is illuminated with radiation of double the wavelength, then the stopping potential becomes $1.6$ volts. Then the threshold wavelength for the surface is
- A$2\lambda$
- ✓$4\lambda$
- C$6\lambda$
- D$8\lambda$