Question

The work function of a metal is 4 eV. If EMR of 200 nm fall on the metal surface. Calculate the maximum K.E. of photo electron effect.

Answer 1

2.2

Answer 2

To calculate the maximum kinetic energy (K.E.) of the photoelectron, we use Einstein's photoelectric equation:

$K.E._{max} = E - \Phi$

where:

$E$ is the energy of the incident electromagnetic radiation (photon).

$\Phi$ is the work function of the metal.

Given:

Work function ($\Phi$) = 4 eV

Wavelength of EMR ($\lambda$) = 200 nm

First, calculate the energy of the incident photon ($E$). We can use the simplified formula that relates energy in electron volts (eV) to wavelength in nanometers (nm):

$E (\text{eV}) = \frac{1240}{\lambda (\text{nm})}$

Substitute the given wavelength:

$E = \frac{1240}{200} \text{ eV}$

$E = 6.2 \text{ eV}$

Now, substitute the values of $E$ and $\Phi$ into the photoelectric equation:

$K.E._{max} = E - \Phi$

$K.E._{max} = 6.2 \text{ eV} - 4 \text{ eV}$

$K.E._{max} = 2.2 \text{ eV}$

The maximum kinetic energy of the photoelectron is 2.2 eV.