# refractive index of glass with respect to air is 3/2..refractive index of water with respect to air is 4/3..what is the refractive index of glass with respect to water?? is it 3/2 divided by4/3 or 4/3 divided by 3/2??

let speed in glass be z,water be y and air be x

3/2 = x/z

z = 2x/3

4/3 = x/y

y = 3x/4

RI of glass with respect to water is = 3x/4 * 3/2x = 9/8 = 1.125

• -6

nga = a / g  nwa= a / w

3 / 2 = a / g  4 / 3 = a / w

g = 2 / 3 a  w = 3 / 4 a

NOW ,  ngw  = 3/4 a  divided by    2/3 a

ngw   =  9 / 8

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Hi Reshma !!!!

let speed of light in air = c1 ... speed in water = c2 ..... speed in glass = c3 .....

anw = c1 / c2 ..... ang = c1 / c3  ...... wng = c2 / c3 ...... [ according to formula ]

now , anw * wng = c1 / c2 * c2 / c3 = c1 / c3 = an

-----> wngang /   anw

-----> wng = (3/2) / (4/3) = 9 / 8 .....

Hope this helps !!!!!

• 24

answers were confusing..but still i understood...thnx everyone..:) thumbs up for all!

• -13

good question

THANX

• -4
I have an easier method.
Refractive index of water with respect to air is = 4/3
Refractive index of glass with respect to air is = 3/2

Now take LCM of 2 & 3. It will be six. Now what multiplied to 3 gives 6? 2. Therefore multiply denominator and numerator with 2 for nwa​.
Thus we get 8/6

Now what multiplied to 2 gives 6? 3. Therefore multiply denominator and numerator with 3 for nga.
Thus we get 9/6

Now just arrange the numerators of the obtained fractions from above and we get,
Refractive index of glass with respect to water = 9/8  =ngw

Some tips:
• Take LCM of the denominators if the mediums are with respect to the same medium (air, vacuum, water, etc.)
• It is easier to work with like fractions.
Hope this helped! Cheers.

• 6
refractive index= c/v = speed of light in air or vacuum/speed of light in given medium
refractive index of glass= speed of light in air or vacuum/speed of light in glass
​refractive index of water= speed of light in air or vacuum/speed of light in water
given:
refractive index of glass=3/2
refractive index of water=4/3
refractive index of glass with respect to water=3/2/4/3 =9/8 =1.125

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Awesome method Vineeta Thakvani.I am really helped.Thank You very much
• -12
• Thanx Gopika , Ur Answer is Amaze....
• 5
ngw=9/8
• -8
Nga = a/g Nwa = a/w
3/2=a/g , 4/3 = a/w
g= 2/3 w= 3/4
Ngw = 3/4 divided by 2/3 a
Ngw = 9/8
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• -7
It is 3/ 2 and 4/3
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Like pls😊👍

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