Final answer:
The index of refraction of a substance can be determined from its critical angle when submerged in water by using the sine of the critical angle and the known index of refraction of water, which is 1.333.
Step-by-step explanation:
To determine the index of refraction of a substance based on its critical angle when it is submerged in water, we can use Snell's Law and the concept of total internal reflection. The critical angle can be found using the formula: sin(critical angle) = index of refraction of water / index of refraction of the substance. Given that the index of refraction of water is approximately 1.333 and the critical angle is given as 68.4°, we can solve for the unknown index of refraction.
By re-arranging the formula we get: index of refraction of the substance = index of refraction of water / sin(critical angle).
Plugging in the values, we have: index of refraction of the substance = 1.333 / sin(68.4°).
Calculating this gives us a value that we can then compare to the provided options (A) 0.75, (B) 1.33, (C) 1.50, (D) 2.25 to find the best match.