Photoelectric Effect

Step 1: Apply Einstein's photoelectric equation
The maximum kinetic energy

K_%7B%5Ctext%7Bmax%7D%7D

is given by:

K_%7B%5Ctext%7Bmax%7D%7D%20%3D%20h%5Cnu%20-%20%5Cphi%20%3D%20E%20-%20%5Cphi

where: -

E%20%3D%204.25%20%5C%2C%20%5Ctext%7BeV%7D

(photon energy) -

%5Cphi%20%3D%202.25%20%5C%2C%20%5Ctext%7BeV%7D

(work function)
Step 2: Calculate kinetic energy in eV

K_%7B%5Ctext%7Bmax%7D%7D%20%3D%204.25%20%5C%2C%20%5Ctext%7BeV%7D%20-%202.25%20%5C%2C%20%5Ctext%7BeV%7D%20%3D%202.00%20%5C%2C%20%5Ctext%7BeV%7D

Step 3: Convert eV to Joules
Using

1%20%5C%2C%20%5Ctext%7BeV%7D%20%3D%201.6%20%5Ctimes%2010%5E%7B-19%7D%20%5C%2C%20%5Ctext%7BJ%7D

K_%7B%5Ctext%7Bmax%7D%7D%20%3D%202.00%20%5Ctimes%201.6%20%5Ctimes%2010%5E%7B-19%7D%20%5C%2C%20%5Ctext%7BJ%7D%20%3D%203.2%20%5Ctimes%2010%5E%7B-19%7D%20%5C%2C%20%5Ctext%7BJ%7D

Step 4: Verify calculation

2.00%20%5C%2C%20%5Ctext%7BeV%7D%20%5Ctimes%20%5Cfrac%7B1.6%20%5Ctimes%2010%5E%7B-19%7D%20%5C%2C%20%5Ctext%7BJ%7D%7D%7B1%20%5C%2C%20%5Ctext%7BeV%7D%7D%20%3D%203.2%20%5Ctimes%2010%5E%7B-19%7D%20%5C%2C%20%5Ctext%7BJ%7D

Step 5: Match with options
The calculated value matches option (c).

Chapter Questions
1 MCQs