Holmarc's Liquid Lens Apparatus (Model No: HO-ED-O-01) is designed for the determination of refractive index of a given liquid. With its new design and features, one can easily understand the principles and practices involved.

The theory behind the liquid lens is based on the properties of one or more liquids to create magnifications within a small amount of space. The focus of a liquid lens is controlled by the surface of the liquid. The surface profile of the liquid determines the focal length of liquid lens system and how the liquid lens focuses light rays.

This apparatus consists of graduated vertical post with rigid base along with a light source and required optics. A pointer illuminated with LED is mounted on the vertical post. The illumination helps to conduct the experiment even in low light conditions. The pointer is free to move along the axis of the vertical post and can be easily clamped at desired positions.
The liquid lens arrangement is kept on a rigid base. The pointer is raised or lowered till the tip of its image coincides with the tip of the pointer without parallax. The distances of the pointer from the top and bottom of the lens are measured. The experimental setup includes three convex lenses of different focal lengths and a plane mirror. A petri dish carrying liquid is also included in this setup.

Experiment:

   To determine the focal length of convex lens.
   To determine the focal length of liquid lens.
   To find the refractive index of liquid.