Question

What is interference of light? Mention the condition for (A) constructive and (B) destructive interference. 
 

Hint:

Interference occurs when two light waves superpose. Constructive interference occurs when the path difference is \( m\lambda \), and destructive interference occurs when the path difference is \( (m + 1/2)\lambda \).

Answer 1

Interference of Light:

Interference is the phenomenon that occurs when two or more light waves superpose to form a resultant wave. Depending on the phase relationship between the waves, the interference can be constructive or destructive.

Condition for Constructive Interference:

When the path difference between the waves is an integer multiple of the wavelength \( m\lambda \), the waves interfere constructively:

\[ \Delta x = m\lambda, \quad m = 0, 1, 2, \dots \]

Condition for Destructive Interference:

When the path difference is an odd multiple of half the wavelength \( (m + 1/2) \lambda \), the waves interfere destructively:

\[ \Delta x = (m + 1/2)\lambda, \quad m = 0, 1, 2, \dots \]