A step index fibre has a relative refractive index difference of 0.9%.Estimate the critical angle at the core -cladding interface,when the core index is 1.46.find the numerical aperture,if the source to fiber medium is air.

Explanation

To solve the problem, we will follow these steps:

### Step 1: Identify the Given Data
- Relative refractive index difference (Δn) = 0.9% = 0.009 (as a decimal)
- Core refractive index (μ1) = 1.46
- Refractive index of air (μ_air) = 1

### Step 2: Calculate the Cladding Refractive Index (μ2)
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