The refractive index of a medium tells us how much it slows down and bends light compared to a vacuum. The universally accepted refractive index of **water is approximately 1.33.
Refractive Index of Water: 1.33.
Refractive Index of Air: 1.0003 (≈ 1).
Refractive Index of Glass: 1.5.
Refractive Index of Diamond: 2.42 (highest of common materials).
Formula: μ = c/v.
A refractive index of 1.33 means that light travels 1.33 times slower in water than it does in vacuum/air. The speed of light in vacuum is 3×10⁸ m/s, so in water it is approximately 2.25×10⁸ m/s.
Formula: μ = c/v = Speed of light in vacuum / Speed of light in medium.
When light passes from air into water, it bends according to Snell's Law: μ₁ sin θ₁ = μ₂ sin θ₂ For air to water: 1 × sin θ₁ = 1.33 × sin θ₂ Since 1.33 > 1, the light bends toward the normal when entering water.
When you look at a straw in a glass of water, it appears bent or broken at the water surface. This is because the light from the submerged part bends as it exits the water, making the straw appear displaced from its actual position.
The refractive index of water is approximately 1.33.
It means light travels 1.33 times slower in water than in vacuum, causing it to bend toward the normal when entering water.
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