What is the condition for diffraction to take place ?

Explanation

### Step-by-Step Solution:

1. **Understanding Diffraction**:
- Diffraction refers to the bending of waves around obstacles and the spreading of waves when they pass through small openings (slits). It is a phenomenon that occurs with all types of waves, including light waves.

2. **Condition for Diffraction**:
- For diffraction to be observable, the size of the slit (denoted as 'b') must be comparable to the wavelength of the light (denoted as 'λ'). This means that the dimensions of the slit should be on the same order of magnitude as the wavelength of the light being used.

...