MCQ
Light of wavelength $\lambda$ strikes a photo$-$sensitive surface and electrons are ejected with kinetic energy $E.$ If the kinetic energy is to be increased to $2E,$ the wavelength must be changed to $\lambda$ where
- A$\lambda^{\prime}=\frac{\lambda}{2}$
- B$\lambda^{\prime}=2 \lambda$
- ✓$\frac{\lambda}{2}<\lambda^{\prime} < \lambda$
- D$\lambda^{\prime}>\lambda$