Two slits of width a and separation d are illuminated by a coherent beam of light of wavelength `lambda`. What is the linear separation of the bright interference fringes observed on a screen that is at a distance D away?

Explanation

To solve the problem of finding the linear separation of the bright interference fringes observed on a screen that is at a distance D away from two slits of width a and separation d, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Setup**: We have two slits separated by a distance \( d \) and illuminated by coherent light of wavelength \( \lambda \). The screen is at a distance \( D \) from the slits.

2. **Identify the Condition for Bright Fringes**: The condition for constructive interference (bright fringes) is given by:
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