Question

The refractive index of glass is 1.54 and the speed of light in air is 3x 10' m/s.
Calculate the speed of light in water?
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Answer 1

Correct Question

The refractive index of glass is 1.54 and the speed of light in air is 3 × 10^8 m/s. Calculate the speed of light in water?

Solution

Given that, the refractive index of glass is 1.54 and the speed of light in air is 3 × 10^8 m/s.

We have to find the speed of light in water.

Now,

Refractive index in a medium = (Speed of light in vacuum)/(Speed of light in a medium)

As per given condition Refractive index of glass is 1.54 and speed of light is 3 × 10^8 m/s.

So,

Refractive index of glass = (Speed of light in air)/(Speed of light in water)

Substitute the known values in the above formula,

→ 1.54 = (3 × 10^8)/(Speed of light in water)

→ Speed of light in water = (3 × 10^8)/1.54

→ Speed of light in water = 1.9 × 10^8 = 2 × 10^8 (approx.)

Therefore, the speed of light in water is 2 × 10^8 m/s.

Answer 2

Answer:   2×10⁸ m/s

Explanation:

Given,

Refractive index of glass (n) = 1.54

Speed of light in vacuum (c) = 3×10⁸ m/s

Speed of light in water (v) =?

Now we know that,

$\frac{c}{v}=n$

$\frac{3*10^{8} }{v}=1.54\\\frac{3*10^{8} }{1.54}=v\\ v=2*10^{8} m/s$  

The speed of light in water is 2×10⁸ m/s.