Question

what is critical angle? how it is related to refractive index of medium​

Answer 1

When the angle of refraction is equal to 90°, the angle of incidence is called the critical angle, At any angle of incidence greater than the critical angle, the light cannot pass through the surface - it is all reflected

Answer 2

$\huge\bf\red{Answer..}$

⚫When the angle of refraction is equal to 90°, ➡️the angle of incidence is called the critical angle, At any angle of incidence greater than the critical angle, the light cannot pass through the surface - it is all reflected.

➡️The conditions for total internal reflection

are the the light is travelling from an optically denser medium (higher refractive index) to an optically less dense medium (lower refractive index) and that the angle of incidence is greater than the critical angle.

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