# Working of liquid lens

we were recently introduced to the liquid lens in school, but i havent quite understood the working of it. I realize that the curvature of the lens is changed by some process, but i dont exactly know what, and how it would work. Itd also be great if you could mention what factors would affect the focal length/ working of a liquid lens.

Considering the physical principles behind it, a liquid lens is no different from a solid one. The focal length $$f$$ is affected by the refractive index $$n$$ of the lens material (assuming a refractive index of 1 in the surrounding medium) and the curvatures $$R_1$$ and $$R_2$$ of the two surfaces of the lens, as well as it's thickness $$d$$. It holds $$\frac 1f = (n-1) \left( \frac{1}{R_1} - \frac{1}{R_2} + \frac{(n-1)d}{nR_1R_2} \right),$$ which can also be found at wikipedia and is known as the lensmaker's equation.