In this paper, a simple method is described for visually demonstrating that the wavelength of light reduces when entering a medium of higher refractive index. When a violet laser (405 nm) is reflected off the surface of a Blu-ray disc (track spacing 320 nm) diffraction cannot occur since the wavelength is greater than the track spacing. However,…

The refractive index is a number that governs how light changes its direction of propagation as it enters one material medium from another. This phenomenon is known as refraction and the angles of incidence and refraction of light, referred to the normal to the interface of the two media at the point of incidence, are related by Snell's law. The…

The laser pointer has been widely used to demonstrate some simple optics phenomena, like reflection, refraction, total reflection, and diffraction. However, the rays of laser light cannot be seen in the air because the scattered light is too weak. Many physics teachers use milk or smoke to visualize rays of laser light in physics labs, but it is…

A diffraction grating is a plane surface having a large number of closely spaced slits running in parallel. When light of appropriate wavelength is incident on a diffraction grating it functions as a spectrometer, able to separate the light into its spectral components. Physical examples of interest for diffraction in the real world are…

In this paper, we propose a simple yet generic and versatile method to measure the position of a moving body as a function of time. Apart from very basic equipment such as carts and wheels, only a laser pointer or a similar device and a smartphone are necessary. By attaching a source of light to a cart and video filming its movement on a…

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…

This study aims to measure Brewster's angle of glass and acrylic brick with an easy-to-obtain mobile application (app) by changing the tungsten light source to a red laser. The popularization of the smartphone has inspired many to use its various built-in sensors to carry out general physics experiments. Many others have adopted both a laser and a…

The Arduino board and its communication with several sensors are becoming more and more popular in the physical science community. They offer inspiring possibilities for learning different physical concepts. In this article, we focused on creating a very practical educational system for experimenting with diffraction of laser light and graphically…

Fluorescence spectra excited by laser pointers have been the subject of several papers in "TPT". These papers all describe a fluorescence phenomenon in which the reflected laser light undergoes a change in color: this color change results from the combination of some partially reflected laser light and additional colors generated by…

Students often have difficulties comprehending situations in which wave characteristics of light are manifested. After teaching wave optics, we studied the level of understanding of reflective diffraction of light with a group of secondary school students, and the phenomenon of diffraction in general. We analysed the possibility of using…

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 ±…

This paper presents an argumentation-based demonstration experiment to teach the light-matter interaction using an observable laser beam and vacuum pump. In the experiment, the concept of darkness was addressed using a virtual space environment created by gradually decreasing the pressure inside a quartz glass bell jar with a vacuum pump. This…

This paper describes the use of a tabletop electron microscope in teaching college level physics. The workings and use of an electron microscope encompass many aspects of science, technology, engineering and mathematics (STEM). A sequence of activities was constructed to compliment the instructional material in the physics course of the University…

The lifetimes of the photoluminescent compounds contained in the coating of fluorescent compact lamps are usually measured using specialised instruments, including pulsed lasers and/or spectrofluorometers. Here we discuss how some low cost apparatuses, based on the use of either sensors for the educational lab or commercial digital photo cameras,…

Understanding the inverse square law, how for example the intensity of light or sound varies with distance, presents conceptual and mathematical challenges. Students know intuitively that intensity decreases with distance. A light source appears dimmer and sound gets fainter as the distance from the source increases. The difficulty is in…