Variations in Temperature wil also effect the density of fluid. The Newton's rings set up (Lens over the glass plate) is placed on tripod and subjected to heat by placing a candle underneath the glass plate. when the heat is applied, the concentric circular bright and dark fringes (with Sodium light) appear to rush towards the center and vice versa when heat is withdrawn as shown in video clip-1b with Sodium light and video clip-1c with white light.

If an ice cube is used instead of heat, contrary effect has been witnessed. That is the fringes rush away from the center when the ice cube is applied underneath the glass plate and vice versa. When heat is applied the density of the complex fluid at the center gets reduced where by the fringes get repositioned in accordance with the density changes. That is why they appear to be rushing towards the center. When the heat is withdrawn, the density of the complex fluid gradually reverts to its original state and the fringes again get repositioned. That is why the fringes appear to be rushing away from the center.

When the lens is placed on a glass plate the projections on the glass plate are found obstructing the movement of the fringes when temperature variations take place. Where as no such problem is encountered when acrylic sheet or a piece of CD (Compact disk) is used. So, when a glass plate is used to get the Newton's rings, it is advisable to place the lens about 1/4th of a mm above the glass plate, so that the movement of fringes in the complex fluid is not hindered.