Index of Refraction Calculator
The index of refraction calculator will allow you to calculate the refractive index of any medium. It is also a valuable tool for determining the speed of light in any translucent material. Continue reading to discover the index of refraction formula and learn how to find the index of refraction.
Refractive index definition
The index of refraction, also called the refractive index, describes how light propagates through a medium. It is a dimensionless quantity, and it determines how much light is bent (or refracted) when entering a different medium. In essence, refraction means a change in the speed and wavelength of the wave.
Learn more about waves and their properties in our wavelength calculator or through our frequency calculator.
🙋 We can also observe refraction in the magnification of images through a lens. Expand your knowledge about lenses by checking out our thin lens equation calculator or our lens maker equation calculator.
Index of refraction formula
Index of refraction of any medium is defined as the proportion between the speed of light in vacuum and in the investigated medium. The refractive index equation is:
where:
- nn — Refractive index;
- cc — Speed of light in vacuum – 299,792.46 km/s; and
- vv — Speed of light in the medium.
The typical values for the refractive index are between 1 and 2, but there are some higher values. As nothing can travel faster than with the speed of light, there are no materials with an index of refraction lower than 1.
How to find the index of refraction
- Determine the speed of light in the analyzed medium. For example, let's assume 228,850 km/s228,850 km/s.
- Divide the speed of light by this value. 299,792.46/228,850=1.31299,792.46/228,850=1.31.
- The obtained value is the refractive index of the medium.
- You can use this value to calculate the angle of refraction, using our Snell's law calculator.
You can also take the value of the refractive index directly from the list below.
- Vacuum: 1 (by definition)
- Air: 1.000293
- Water at 20 °C: 1.333
- Ethanol: 1.36
- Ice: 1.31
- Diamond: 2.419
FAQs
- What does the index of refraction directly measure?
- The index of refraction is a measure of how fast light travels through a material compared to light traveling in a vacuum. For example, a refractive index of 2 means that light travels at half the speed it does in free space.
- What is the refractive index of water?
- The refractive index of water is 1.333 if the temperature of the water is 20 °C. As you increase the temperature, the water becomes less dense, light travels faster, and the refractive index decreases.
- What is the refractive index of glass?
- The glass used for windows has a refractive index of 1.52. The refractive index for other types of glass are: Fused silica — 1.458 Pyrex — 1.470 Crown glass — 1.50-1.54 Flint glass (pure) — 1.60-1.62 Flint glass (impure) — 1.523-1.925
- What is the SI unit of refractive index?
- Refractive index doesn't have any SI units, as it is a unitless, dimensionless quantity. This result is because you calculate it by dividing the speed of light in a vacuum by the speed of light in the material.
- How to calculate speed of light using refractive index?
- You can calculate the speed of light by multiplying the refractive index of a material by the speed at which light travels through the same material. That means by carefully choosing the right material, measuring the speed of light is easier.
- How does sugar concentration affect the refractive index of water?
- The addition of sugar to water will make it denser, slowing light down and so increasing the refractive index of the solution.
Related calculators
Acceleration
The acceleration calculator estimates acceleration using three different approaches – velocity difference, distance traveled over time, and net force vs. mass.
Physics
Density
Use the density calculator to instantly find how tightly packed an object's molecules are.
Physics
Free fall
Our free fall calculator can find the velocity of a falling object and the height it drops from.
Physics
Projectile motion
Use our projectile motion calculator to analyze a projectile in parabolic motion.
Physics