Reflection of Light on a Water Tank, Lab Report Example


This work highlights a report based on the findings from the laboratory on the Reflection of light on a water tank. The study looks at the behavior of light when it reaches on the surface of water tank. This work lays emphasize on the reflection of light on the surface of a transparent water tank. The study specifically focuses on a transparent and reflective water tank whereby reflection occurs on the surface and subsequent effect that causes internal reflection inside the transparent water tank.

Apparatus and methods

This study relied on the following apparatus for delivery of reliable and good results.

  • Source of light such as an electric bulb a laser is preferable for the study.
  • A paper whole punch
  • Transparent water tank with a regular surface
  • A few chalk dust
  • Procedure and methods
  • Fill the transparent water tank with water
  • Drop the chalk dust on one side of the water tank
  • Direct the light source to travel through the punch hole, the light should be focused to a produce a good beam that is strong enough to be visible the punched hole on the paper and the light beams should be used to produce an index.
  • The chalk dusts on side of the water enhance visibility of the light beam as it strikes the surface and travels into the water.
  • Wait for at least 10 minutes for the chalk dust to settle as they are dropped bit by bit into the tank.
  • Direct the light beam on the surface of the tank.


As the beam hits the surface of the water tank, one is able to observe two fold effects whereby the reflected light on the surface of the water tank is refracted in the water, the chalk dust in the water tanker will appear thicker which a good manifestation of refraction is.  The punched hole on the paper can be used to change the direction of the beam to different locations to enable more realistic observations (Ehrlich, Robert, p345).

The light beam from the source is the incident beam which is reflected and refracted as shown in the diagram below.

The light beam from the source is the incident beam which is reflected and refracted as shown

The longer the distance between the light source the water surface, the greater  the angle of incidence. As light moves from air into the water its speed reduces and hence refraction which makes the chalk dusts to appear thicker than their actual size. The critical angle determines the occurrence of internal reflection, while the angle of incidence determines the refractive index between the two surfaces as the light moves from one object to another.  When the beam is straightened and thereby striking the surface at 90 degrees, the refraction effect reduces, a good angle such as 45 degrees gives the best results (Ehrlich, Robert, p345).


Reflection of light on surface of a transparent water   tank is used to explain the element of total internal reflection.  The disparity in the critical angle between the two surfaces is very cardinal in determining the refractive index of the two surfaces (Axelrod, p678).

Total internal reflection is applied in real life situation in the telecommunication sector where optical fibers work the principle of light refraction to transmit data. Special kind of binoculars such as prismatic ones employs the concept of total internal reflection to enhance the visibility of images (Moreno, Ivan, p 914).

Works cited

Ehrlich, Robert .Why toast lands jelly-side down: zen and the art of physics demonstrations. Princeton, New Jersey, USA: Princeton University Press. p. 182. ISBN 0-691-02891-5. 2012.

Moreno, Ivan. “Thin-film spatial filters”    (PDF). Optics Letters 30 (8): pp. 914–916.             Bibcode:2005OptL…30..914M.doi:10.1364/OL.30.000914. PMID 15865397.2009

Axelrod, Dn .”Cell-substrate contacts illuminated by total internal reflection fluorescence“. The Journal of Cell Biology 89 (1): 141–145. doi:10.1083/jcb.89.1.141. PMC 2111781. PMID 7014571.2008.

External linksMandelstam, L.I. “Light Scattering by Inhomogeneous Media”. Zh. Russ. Fiz-Khim. Ova. 58: 381. 2008