determine the time it takes for light to travel 54 cm through gycerine in an aquarium.?

Answer 1

refractive index of glycerine (u) =1.473
it will take same time as it would take in vaccum
t = distance / speed = 54 / 3*10^8 = 1.8*10^-7 sec
t = 0.18 micro second
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time = distance / speed
in another medium, both distance travelled and speed with which travelled "Change" due to refractive index, they change in such a fashion - so as to keep the time taken as same
t = {d/u1} / [c/u1] = {d/u2} / [c/u2] ........
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golden rule >>
> if there are 3 parameters in a formula
> only 2 can vary at a time upon change of surroundings, so that
> the THIRD remains constant
>> this is the very basis of "keeping sign of { = } euality" INTACT, or formula will become INDETERMINATE

Answer 2

If I recall the factor correctly, light travels one foot in a nanosecond through air. You need to go less distance through a slower medium, so I will guess both factors cancel and still say a nanosecond. Do you need a closer answer? I can calculate it more carefully but on a practical basis that seems pretty close.