Photoelectric Effect

Step 1: Understanding the photoelectric effect.
The energy of the ejected electrons is
given by the equation:

K.E.%20%3D%20E_%7B%5Ctext%7Bphoton%7D%7D%20-%20%5Cphi

where

K.E.

is the kinetic energy of the ejected electron,

E_%7B%5Ctext%7Bphoton%7D%7D

is the energy of the incident photon, and

%5Cphi

is the work function of the metal.
Step 2: Calculating kinetic energies for each photon.
- For the photon with energy 1 eV:

K.E.%20%3D%201%20%5C%2C%20%5Ctext%7BeV%7D%20-%200.5%20%5C%2C%20%5Ctext%7BeV%7D%20%3D%200.5%20%5C%2C%20%5Ctext%7BeV%7D

- For the photon with energy 2.5 eV:

K.E.%20%3D%202.5%20%5C%2C%20%5Ctext%7BeV%7D%20-%200.5%20%5C%2C%20%5Ctext%7BeV%7D%20%3D%202%20%5C%2C%20%5Ctext%7BeV%7D

Step 3: Finding the ratio.
The ratio of kinetic energies is:

%5Cfrac%7BK.E._%7B1%5C%2C%5Ctext%7BeV%7D%7D%7D%7BK.E._%7B2.5%5C%2C%5Ctext%7BeV%7D%7D%7D%20%3D%20%5Cfrac%7B0.5%7D%7B2%7D%20%3D%20%5Cfrac%7B1%7D%7B4%7D

Thus, the correct answer is
(C) 1 : 2.

Chapter Questions
1 MCQs