(i) In Young's double slit experiment the condition for (a) constructive and (b ) destructive interference at a point on the screen .

Explanation

### Step-by-Step Solution:

**Step 1: Understanding the Setup of Young's Double Slit Experiment**
- In Young's double slit experiment, two coherent light sources (slits) produce an interference pattern on a screen. The light waves from the two slits interfere with each other, leading to bright and dark fringes on the screen.

**Step 2: Path Difference Formula**
- The path difference (Δx) between the two waves reaching a point on the screen is given by the formula:
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