Q51 / 180 · COMEDK 2026 (9 May Shift 1) · Chemistry
In the photoelectric emission, the energy of the emitted electron is:
- Agreater than the energy of the incident photon
- Bproportional to the intensity of the incident photon
- Csame as that of the incident photon
- Correct answerDsmaller than the energy of the incident photon
Solution
According to Einstein's photoelectric equation, the maximum kinetic energy of the emitted electron is given by:
$K_{\max} = E - \Phi$
where $E$ is the energy of the incident photon and $\Phi$ is the work function of the material.
Since the work function $\Phi$ is always positive for any material, the maximum kinetic energy $K_{\max}$ is strictly less than the energy of the incident photon $E$.
The actual kinetic energy of an emitted electron ranges from $0$ to $K_{\max}$.
Therefore, the energy of the emitted electron is always smaller than the energy of the incident photon.
Answer: smaller than the energy of the incident photon
$K_{\max} = E - \Phi$
where $E$ is the energy of the incident photon and $\Phi$ is the work function of the material.
Since the work function $\Phi$ is always positive for any material, the maximum kinetic energy $K_{\max}$ is strictly less than the energy of the incident photon $E$.
The actual kinetic energy of an emitted electron ranges from $0$ to $K_{\max}$.
Therefore, the energy of the emitted electron is always smaller than the energy of the incident photon.
Answer: smaller than the energy of the incident photon
Hence, the correct answer is option: 'D'.