Question

The work function of a metal is $3.0eV$, then which of the following can cause photoelectric emission?

• A. $414nm$
• B. $300nm$
• C. $200nm$
• D. all of the above

Answer 1

The correct option is D all of the above

For emission incident photon must have higher energy than work function.

$\Rightarrow \frac{hc}{\lambda }\ge \varphi$

$\Rightarrow \frac{1242}{\lambda }\ge 3$

$\Rightarrow 414\ge \lambda$

$\therefore {\lambda }_{max}=414nm$