Chapter 27.1, Problem 16SSC

To determine

To Explain: High-intensity low-frequency light is not able to emit electrons from metal but low-intensity high-frequency light can emit electrons.

Explanation of Solution

Introduction:

The threshold energy is the factor that is considered in photoelectric effect to determine whether photoelectric electrons would eject out or not.

The photo electric effect exhibits particle nature of light where threshold energy plays a crucial role.

As stated the energy of light particle (photon) is

  $E=h\nu$

As per photoelectric effect

  $\begin{array}{l}{E}_k=h\nu -\varphi \\ E_k=hv-h{v}_0\end{array}$

Photoelectric effect is a phenomenon in which an incident ray falls on a shiny metal surface and electrons are ejected. The incident energy should be at least equal to the threshold energy. So, when frequency of light is at least equal to threshold frequency, the electron is ejected.

Intensity affects the amount of photocurrent but whether an electron would eject or not depends on the frequency of the incident radiation.

Conclusion:

The low intensity, high frequency light is able to eject the electron is because the frequency of photon is more than threshold frequency whereas, high − frequency, low frequency cannot reach threshold limit.