Question

The photoelectric threshold wavelength of a certain metal is $3000\mathring{A}$ . If the radiation of $2000\mathring{A}$ is incident on the metal.

• A. Electrons will be emitted
• B. Positron will be emitted
• C. Protons will be emitted
• D. Electrons will not be emitted

Answer 1

Answer: (A)

$W_o=\frac{hc}{{\lambda }_o}$
Energy of the radiation of wavelength $2000\mathring{A}$ is greater than the energy of $3000\mathring{A}$ hence we know
$e{V}_o=\frac{hc}{\lambda }-\frac{hc}{{\lambda }_o}$
$\therefore$ electron will be emitted.