Question

It's nighttime, and you've dropped your goggles into a 3.1-mm-deep swimming pool. If you hold a laser pointer 1.2 mm above the edge of the pool, you can illuminate the goggles if the laser beam enters the water 1.8 mm from the edge.
How far are the googles from the edge of the pool?

Answer 1

Answer:

the googles are 4.33mm from the edge

Explanation:

In this question, we are asked to calculate the distance of a set of googles from the edge of a pool.

We proceed as follows;

depth of pool , d = 3.1mm

Now, let i be the angle of incidence

i = arctan(1.8/1.2)

i = 56.31 degree

Using snell's law ,

n1 * sin(i) = n2 * sin(r)

1 * sin(56.3) = 1.33 * sin(r)

r = 38.72 degrees

Now,

distance of googles = 1.8+ d*tan(r)

distance of googles = 1.8+ 3.1 * tan(38.72)

distance of googles = 4.3 mm