A coin is resting on the bottom of an empty container. The container is then filled to the brim three times, each time with a different liquid. An observer (in air) is directly above the coin and looks down at it. With liquid A in the container, the apparent depth of the coin is 7 cm, with liquid B it is 6 cm, and with liquid C it is 5 cm. Rank the indices of refraction of the liquids in descending order (largest first). a. nA, nB ,nC
b. nA, nC ,nB
c. nC, nA ,nB
d. nC, nB ,nA

Explanation:

index of refraction = real depth / apparent depth .

apparent depth is in the denominator so as it decreases , index of refraction increases .

Apparent depth is least for C , so index of refraction of C will be greatest .

So required order largest to least is C , B , A.

d ) is the correct option.

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it