Question

When green light is incident on a metal, photo electrons are emitted by it but no photo electrons are obtained by yellow light. If red light is incident on that metal then:

• A. No electron will be emitted
• B. Less electrons will be emitted
• C. More electrons will be emitted
• D. We can not predict

Answer 1

The correct option is A No electron will be emitted

Wavelength of $Red>Yellow>Green$

(learn the pattern $VIBGYOR$)
$\frac{hc}{\lambda }=\frac{hc}{{\lambda }_0}+K.E$
$\therefore$ As we increase $\lambda$, photo electric effect doesn't take place.
If there is no photo electron emission for yellow light, there would be no emission even for red light.