Question

The refractive index of glass is 1.5. The speed of light in air is \(3 \times 10^8\) m/s. The speed of light in glass will be

• A. \(3 \times 10^8\) m/s
• B. \(2 \times 10^8\) m/s
• C. \(4.5 \times 10^8\) m/s
• D. \(2.25 \times 10^8\) m/s

Hint:

The refractive index is the ratio of the speed of light in a vacuum to the speed of light in the medium. In this case, the speed of light in glass is calculated by dividing the speed of light in air by the refractive index.

Answer 1

The Correct Option is B

Step 1: Understanding the Formula for Speed of Light in a Medium
The speed of light in any medium is given by the formula: \[ v = \frac{c}{n} \] where: - \(v\) is the speed of light in the medium - \(c\) is the speed of light in vacuum (which is \(3 \times 10^8\) m/s) - \(n\) is the refractive index of the medium

Step 2: Applying the Formula
Given that the refractive index of glass is \(n = 1.5\), and the speed of light in air is \(c = 3 \times 10^8\) m/s, we can calculate the speed of light in glass as: \[ v = \frac{3 \times 10^8}{1.5} = 2 \times 10^8 \, \text{m/s} \]

Step 3: Conclusion
Thus, the speed of light in glass is \(2 \times 10^8\) m/s. The correct answer is option (B).