The critical angle
(C) for a medium is defined when light passes from a medium of higher refractive index
(n1) into a medium of lower refractive index
(n2), at an angle such that the refracted ray is at
90∘ to the normal. At this angle, light is refracted along the boundary, and for any angle greater than the critical angle, total internal reflection occurs.
The formula to calculate the critical angle is given by:
C=sin‌−1(‌)The refractive index of the first medium
(n1) is given as
√2, and since the second medium would be air or vacuum, we take its refractive index
(n2) to be 1 (since the refractive index of air is approximately 1 for most optical purposes).
Thus, substituting the given values into the formula:
The value of
sin‌−1(‌) is known to be
45∘, which is the angle for which the sine is
‌. Therefore, the correct option is:
Option B:
45∘