Question

Choose the correct option.

There are different fish, monkeys, and water of the habitable planet of the star Proxima b. A fish swimming underwater feels that there is a monkey at 2.5 m on the top of a tree. The same monkey feels that the fish is 1.6 m below the water surface. Interestingly, height of the tree and the depth at which the fish is swimming are exactly same. Refractive index of that water must be

विकल्प

• `6/5`

• `5/4`

• `4/3`

• `7/5`

Answer 1

`5/4`

Explanation:

As, height of the tree = depth at which fish swimming, Real depth, or height in both conditions is same, (say) x.

∴ For monkey, as apparent depth = 1.6 m,

`"n"_"water"/"n"_"air"="Real depth"/"Apparent depth"="x"/1.6`

For fish, as apparent height = 2.5 m,

`"n"_"air"/"n"_"water"="Real height"/"Apparent height"="x"/2.5`

∴ `"x"/1.6xx"x"/2.5` = 1

∴ x² = 4 ⇒ x = 2

∴ `"n"_"water"/"n"_"air"="x"/1.6=2/1.6=5/4`