Huygens' principle in which every point on a propagating wave acts like a point source of radiation is a foundation principle of physics. Normally, Huygens' principle is demonstrated by passing a wave, for example a water or light wave through an aperture comparable in size to the wavelength. In this paper, an experiment is described in which a…

A simple diffraction experiment was designed using banana stem as natural grating. Coherent beams of lasers with wavelengths of 632.8 nm and 532 nm that pass through banana stem produce periodic diffraction patterns on a screen. The diffraction experiments were able to measure the distances between the slit of the banana stem, i.e. d = (28.76 ±…

A container was placed on top of a piece of white paper, and a pin positioned so that it vertically touched an outside wall of the container. Students were asked to predict the image of the pin when it was observed from the top of the container. Two scenarios of either an empty container or a container completely filled with water were considered…

By attaching LEDs and lasers to moving objects, and shining their light on photochromic surfaces below them, we can display traces of many motions of interest in introductory physics courses and science museums.

In this paper of I have reviewed the test done for validating the special theory of relativity using masers and lasers in last one century. Michelson-Morley did the first experimental verification for the isotropy of space for the propagation of light in 1887. It has an accuracy of 1/100th of a fringe shift. The predicted fringe shift on the basis…

A lens based on liquid in the confined volume of a volumetric flask was presented as a potential projector to observe microscopic floating organisms or materials. In this experiment, a mosquito larva from a natural pond was selected as a demonstration sample. By shining a light beam from a laser pointer of any visible wavelength through the…

The word laser is an acronym. It stands for Light Amplification by Stimulated Emission of Radiation. Lasers, invented in 1958, are used to cut and fuse materials, accurately survey long distances, communicate across fiber-optic phone lines, produce 3D pictures, make special effects, help navigation, and read bar codes for cash registers. A laser…

On the occasion of the laser's 50th anniversary, we performed a modern Fizeau experiment, measuring the speed of light with a laser beam passing over the city centre of Marseille. For a round trip distance of almost 5 km, the measurement has reached an uncertainty of about 10[superscript -4], mainly due to atmospheric fluctuations. We present the…

An advanced undergraduate laboratory experiment is outlined which uses a dye laser to map out the chromatic dispersion curve of a polymethyl methacrylate (PMMA) optical fibre. Seven different wavelengths across the visible spectrum are employed using five different dyes. The light pulse is split into two pulses, one to a nearby photodetector and…

Diffusion is a fundamental phenomenon that is vital in many chemical processes such as mass transport in living cells, corrosion, and separations. We describe a simple undergraduate-level experiment based on Weiner's Method to probe diffusion in a ternary aqueous mixture of small molecular-weight molecules. As an illustration, the experiment…

Discusses laser demonstration for invoking interest in science, especially physics. Describes some examples, such as diffraction, scattering, expansion by diverging lens, internal reflection in a light pipe, and illumination through optical cable. Provides some practical hints for the demonstration. (YP)