GENERAL KNOWLEDGE

Detailed explanation-1: -The value of the critical angle is 48.8°

Detailed explanation-2: -Critical Angle can be described as the angle of incidence that offers an angle of refraction of 90 degrees. Remember that the critical angle is defined as an angle of incidence value. The critical angle will be 48.6 degrees for water-air boundaries and 61.0 degrees for crown glass-water boundary.

Detailed explanation-3: -The critical angle is the angle of incidence where the angle of refraction is 90°. The light must travel from an optically more dense medium to an optically less dense medium. Figure 5.15: When the angle of incidence is equal to the critical angle, the angle of refraction is equal to 90°.

Detailed explanation-4: -The critical angle for water is measured between the beam and a line perpendicular to the surface, and is 49 degrees.

Detailed explanation-5: -No refraction takes place. When the wave is at a 90-degree angle to the normal, it is traveling parallel to/alongside the boundary and never enters the new material, so it does not change speed and therefore does not change direction. No refraction takes place.