This tool allows you to explore how the refractive index (n) of water changes with temperature and wavelength. Use the sliders to adjust the parameters and observe the real-time changes in the values and the chart below. This visualization is based on data and models from peer-reviewed physics literature.
Normal Water (H2O)
1.3304
uncertainty of the order ± 0.0002
Heavy Water (D2O)
1.3262
uncertainty of the order ± 0.0002
Difference ($n_{H_2O} - n_{D_2O}$)
0.0042
Refractive Index vs. Wavelength
Key Concepts & Context
This section explains the core physical principles that govern the refractive index of water, which you can observe using the interactive tools above.
Wavelength Dependence (Dispersion)
The refractive index ($n$) changes with the wavelength ($\lambda$) of light. For water in the visible spectrum, as wavelength increases (e.g., from blue to red light), the refractive index decreases. This phenomenon, known as "normal dispersion," is why a prism separates white light into a rainbow. You can see this effect by moving the wavelength slider: notice how the $n$ values drop as the wavelength increases.
Temperature Dependence (Thermo-Optic Effect)
The refractive index is also sensitive to temperature. For water above 4¡C, as temperature increases, its density decreases. Light travels faster through the less-dense medium, causing the refractive index to decrease. This is called the thermo-optic effect. The change is smallÑabout 0.0001 per 1¡CÑbut crucial for high-precision measurements. Observe this by moving the temperature slider.