Sir,(adsbygoogle = window.adsbygoogle || []).push({});

Please help me with this problem.

# A small air bubble in a sphere of 8 cm diameter of a substance having refractive index 1.4 appears to be 2 cm from the surface when looking along the diameter. Find the true position of the bubble.

I solved it in the following way:

Here n1 = 1, n2 = 1.4, v = -2 cm(Virtual image), R = + 4 cm

n2/v + n1/u = (n2 – n1)/R

1.4/-2 + 1/u = 0.4/4

1/u = 0.1 + 0.7 = 0.8

u = 1/0.8

u = 1.25 cm

But the book answer is 2.33 cm. But I get this answer if I do it in a different way.

Here n1 = 1, n2 = 1.4, v = -2 cm(Virtual image), R = + 4 cm

n1/v + n2/u = (n1 – n2)/R

1/-2 + 1.4/u = (1.4 – 1)/4

1.4/u = 0.1 + 0.5 = 0.6

u = 1.4/0.6

u = 2.33 cm

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Air bubble inside a glass sphere problem

**Physics Forums | Science Articles, Homework Help, Discussion**