Question

Defination of critical angle

Answer 1

When the angle of incidence in water reaches a certain critical value, the refracted ray lies along the boundary, having an angle of refraction of 90-degrees. This angle of incidence is known as the critical angle; it is the largest angle of incidence for which refraction can still occur. For any angle of incidence greater than the critical angle, light will undergo total internal reflection.

Answer 2

..CRITICAL ANGLE -WHEN A RAY OF LIGHT PASSES FROM A MEDIUM OF HIGHER OPTICAL DENSITY TO A MEDIUM OF LOWER OPTICAL DENSITY ,THE ANGLE OF INCIDENCE AT WHICH THE ANGLE OF REFRACTION BECOMES 90° IS THE CRITICAL ANGLE.