MCQ
When a metallic surface is illuminated by a light of wavelength $\lambda,$ the stopping potential for the photoelectric current is $3\, V$. When the same surface is illuminated by light of wavelength $2\, \lambda$ the stopping potential is $1\, V$. The threshold wavelength for this surface is
- ✓$4 \lambda$
- B$3.5 \lambda$
- C$3 \lambda$
- D$2.75 \lambda$
