Question

The speed of light is 3 x 10^8 m/s in air, 2 x 10^8 m/s in medium X, and 2.5 x 10^8
m/s in medium Y.
Choose the correct value for refractive index of Y and refractive index of X with
respect to Y
a) 1.5 and 1.25
b) 1.25 and 1.112
c) 1.25 and 1.2
d) 1.2 and 1.25

Answer 1

Explanation:

Glass refractive index is defined as the ratio between the speed of light in the vacuum and the speed of light in the glass.

Refractive index of glass (ng) = Speed of light in vacuum/speed of light in the glass.

ng = (3 ×108)/ (2 ×108)

ng = 1.5

So answer is a) 1.5 and 1.25

Answer 2

$\huge\mathfrak\red{ANSWER}$

D) 1.2 AND 1.25

$\huge\mathfrak\red{EXPLANATION}$

FOR ANY MEDIUM IT'S REFRACTIVE INDEX ID THE RATIO OF SPEED OF LIGHT IN AIR TO SPEED OF LIGHT IN THAT MEDIUM.

= SPEED OF LIGHT IN AIR

SPEED OF LIGHT IN THAT MEDIUM.

NOW REFRACTIVE INDEX OF Y

=

$3 \times {10}^{8} ms \div 2.5 \times {10}^{8} ms$

$= 3 \div 2.5$

$= 1.2$

THEREFORE WE GET REFRACTIVE INDEX OF MEDIUM Y IS 1.2

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NOW IF WE TALK ABOUT REFRACTIVE INDEX OF A MEDIUM WITH RESPECT TO ANOTHER MEDIUM THEN IT WILL BE REFRACTIVE INDEX OF THAT MEDIUM/REFRACTIVE INDEX OF SECOND MEDIUM.

SO REFRACTIVE INDEX OF X WITH RESPECT TO Y

= REFRACTIVE INDEX OF X

REFRACTIVE INDEX OF Y

SO NOW,

REFRACTIVE INDEX OF X

$= = 3 \times {10}^{8} \div 2 \times {10}^{8}$

$= 3 \div 2$

$= 1.5$

THEREFORE NOW WE HAVE REFRACTIVE INDEX OF X AND Y BOTH.

NOW REFRACTIVE INDEX OF X WITH RESPECT TO Y

$= refractive \: index \: of \: x \: \div \: refractive \: index \: of \: y$

$= 1.5\div 1.2$

$= 1.25$

THEREFORE WE GET REFRACTIVE INDEX OF X WITH RESPECT TO Y IS 1.25 .

HENCE CORRECT OPTION IS (D)

D) 1.2 AND 1.25

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BY SCIVIBHANSHU

THANK YOU

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