Which of the following is true about the index of refraction? a) it is always equal

c) It can be equal to 1.00 but it can also be greater than 1.00. It is never less than 1.00.

Explanation:

Refractive index is equal to velocity of the light 'c' in empty space divided by the velocity 'v' in the substance.

Or ,

n = c/v.

Since speed of the light 'v' in any medium is always be less than or equal to speed of the light in the vacuum 'c', thus, the index of refraction is always be greater than or equal to 1.0.

Explanation:

Given:

distance of tent from the closest point on shore-line,

distance between shoreline point and coral reef,

As shown in the schematic by a green dashed line representing the shortest distance (say l) that the visitor runs towards the reef in order to swim a minimum distance which takes least time.

Now on reaching at the shore at this point the visitor will have to swim the least distance due east to reach coral reef.