23c ray photography

A.b. Make the light path as shown in the figure. When the reflected light reaches the interface between the medium and the air, the incident angle i'=r and the refraction angle r'=i can be obtained from the refraction law. If the refracted light PQ is parallel to the incident light DC, ∠POA=∠COA=i, i = 60, and the refraction angle R = I2 = 30.

C, the distance from C to C is s = 4 rcos 30, and the propagation speed of light in the medium is v = CN = 33c. Then the total time from c to c is t = SV = 6rc, so c is correct.

D. If light is incident parallel to CD along EF, according to geometric knowledge, the first angle of refraction is equal to the second angle of incidence, and according to the principle of optical path reversibility, total reflection cannot occur in the dielectric sphere. So, d is wrong.

So choose C.