arXiv subjects

Sanjoy Kumar Pal

Publications and source records attributed to Sanjoy Kumar Pal.

15 recordsLinked to original sources

arXiv2026

A Simple Method of Demonstration of Characteristics of Rainbows Using a Glass of Water and a Few Laser Sources

A rainbow is a captivating natural phenomenon resulting from the refraction, dispersion, and reflection of sunlight within water droplets. Traditional classroom demonstrations often focus on qualitative explanations of the formation of rainbows using prisms or water bowls. This study presents a simple experimental approach to analysing the process of rainbow formation through quantitative analysis using a cylindrical glass filled with water, graph paper, and three semiconductor laser sources emitting red, green, and blue light. By measuring the angles of minimum deviation for different wavelengths, we have found that the experimental values closely match the theoretical predictions. This method offers a hands-on, cost-effective approach to enhance students' understanding of the physics behind rainbows.

physics.ed-ph↗

arXiv2026

Demonstration of magnetic dipole-dipole interaction by using smartphone pressure sensor

In this paper, we present a hands-on activity designed to verify the dependence of the magnetic force between two identical N35 neodymium disc magnets on their separation distance. Utilizing a weight-measuring device incorporating a smartphone pressure sensor placed inside an inflated Ziplock bag, with a glass plate ensuring perfect contact, we measured the magnetic force with high precision. Our results confirm the established inverse fourth power relationship between magnetic force and distance. The linear plot of magnetic force versus the inverse fourth power of distance corroborates the corresponding theoretical model. From the slope of this linear plot, we have calculated the magnetic dipole moment of each magnet, providing a practical validation of theoretical predictions. This methodology also offers an effective approach for educational and experimental verification of magnetic interactions.

physics.ed-ph↗

arXiv2026

Use of smartphone as a density measuring device

In this paper, we have proposed a simple method of measuring the density of a solid material. We have utilized the pressure sensor of a smartphone as a pressure-measuring device. By measuring the values of pressure when a solid object is in air and also in the fully immersed condition in a non-reactive liquid, we have determined the density of the object.

physics.ed-ph↗

arXiv2026

Determining Viscosity of a Liquid with Smartphone Sensors: A Classroom-Friendly Approach Using Damped Oscillations

This study presents a classroom-friendly method for measuring the coefficient of viscosity of a liquid using a smartphone s accelerometer sensor. A metallic ball tied with a spring-mass system and submerged in mustard oil undergoes damped oscillations due to viscous forces. The Phyphox app is used to record the temporal variation of acceleration, from which the damping constant is calculated to determine the coefficient of viscosity of the oil. The experimentally obtained value is further validated using the Tracker app, and this value is shown to be in close agreement with the standard literature. This method provides an accurate, low-cost experiment ideal for educational settings, utilizing smartphone sensors for viscosity measurement.

physics.ed-ph↗

arXiv2026

Study of the effect of electromagnetic damping force on a magnet oscillating near a non-ferromagnetic conducting plate

We have designed an experiment that involves studying the effects of a conducting plate on the motion of an oscillating disc magnet. We have employed the video analysis method by Tracker software to investigate the variation of electromagnetic damping coefficient with distance between the plate and the magnet. This experiment can indeed serve as a valuable educational tool for undergraduate students, covering topics such as damped oscillation, electromagnetic damping, Lenz's law, and eddy currents.

physics.ed-ph↗

arXiv2026

A smartphone-based simple method for determination of the free space permeability

A simple and novel method is designed to determine the free space permeability. This value is computed from the expression of the terminal velocity of a magnet falling through a conducting pipe using the magnetic sensor of a smartphone and a video player. This method deserves its importance because of the accuracy and precision of the results.

physics.ed-ph↗

arXiv2026

Determination of the acceleration due to gravity by studying magnet s motion through a conducting pipe

We determine the acceleration due to gravity (g) in a novel way using a magnetic sensor and video analysis technique of a smartphone. The same applications are used to measure the terminal velocity of a magnet falling through a conducting pipe and the magnetic moment of the magnet from its torsional oscillations. This experiment would appear to be intriguing, as it combines elements of magnetism, terminal velocity, and electromagnetic damping to determine g.

physics.ed-ph↗

arXiv2026

Determination of the magnetic moment of a magnet by letting it fall through a conducting pipe

A novel method is proposed to determine the magnetic moment of a magnet by studying its free-falling motion inside a non-ferromagnetic and conducting pipe. The dynamics of a neodymium magnet falling inside a pipe is tracked by using sound waves of a fixed frequency generated by one smartphone and detecting acoustic resonance in the pipe simultaneously by the other. This tracking technique leads to the measurement of the terminal velocity of the falling magnet, as the interaction between the magnet and the conducting pipe creates viscosity artificially. The result obtained is verified by studying torsional oscillations of the suspended magnet and conforms to the reported value in such a low-cost setup. The experiment is designed with concepts integrating the domains of general physics, electromagnetic induction, and acoustics.

physics.ed-ph↗

arXiv2026

Smartphone-based measurement of magnetic force and demonstration of Newton third law of motion

A fascinating approach to teaching Newton's Third Law using readily available technology is presented in this article. Magnetic forces are measured by using a smartphone's pressure sensor, two ring magnets, and common household items. Students can measure the magnitudes of forces, gain a more tangible understanding of the law, and see how 'action' and 'reaction' are quantitatively equal and opposite.

physics.ed-ph↗

arXiv2026

LiDAR based determination of spring constant using smartphones

A novel use of the LiDAR sensor of a smartphone in introductory physics experiments is discussed in this article. We have determined the spring constant for various combinations of springs using the LiDAR sensor of a smartphone through the phyphox application. An electrical heater coil is used as a spring, and the period of oscillation of a vertical spring-mass system is measured using a LiDAR sensor. The experimental values of spring constants agree with the theoretical values. A high school student can perform this simple experiment in a smart way at home.

physics.ed-ph↗

arXiv2026

A Unified and Economical Approach to Teaching Higher Secondary Electricity Experiments

In both rural and urban educational settings, science education is often hindered by limited access to lab resources and intimidating, complex instruments. This paper introduces a low-cost, homemade experimental apparatus built using a mobile charger, nichrome wire, galvanometer, and digital multimeter that enables educators to perform key higher secondary electricity experiments. The Indigenous Metre Bridge (IMB) has proven to be an intuitive, user-friendly tool that not only bridges theoretical and practical learning but also reduces student apprehension toward lab work. Its simplicity and accessibility exemplify how frugal innovation can transform physics education.

physics.ed-ph↗

arXiv2023

Estimation of the error matrix in a linear least square fit to the data from an experiment performed by smartphone photography

Determination of the Young modulus of a metal bar in the form of a cantilever is an old experimental concept. However, we have taken the advantage of modern advanced technology of smartphone camera to find the load depression graph of the cantilever by taking photographs with the smartphone camera. Smartphone photography allows us to find a precise transverse magnification of an object from the size of the real image formed on the sensor of the camera. Image size on the sensor can be obtained with micron level accuracy. From the load depression graph, we have determined the Young modulus of the bar. The sensitive measurements of the depression of the cantilever at its free end by its own weight, have allowed us to determine the density of aluminium. We have added an analysis of the chi squred minimisation technique for determining the parameters and their uncertainities in a linear fit. Starting from the curvature matrix we have made a comprehensive analysis of the error matrix relevant for a two parameter linear fit. Then we have shown how to form the error matrix for the fitted parameters which includes the covariance term between the two correlated parameters, in the context of our specific experiment. We have propagated the errors in the parameters to find the uncertainties in the Young modulus and the density of the bar. We have shown that a precise measurement is possible by smartphone photography.

physics.ed-ph↗

arXiv2022

Use of a smartphone camera to determine the focal length of a thin lens by finding the transverse magnification of the virtual image of an object

In this work we have determined the focal length of a concave lens by photographing the virtual image of an object by a smartphone camera. We have similarly determined the focal length of a convex lens by forming a virtual image of an object keeping it within the focal distance from the lens. When a photograph is taken by a smartphone, the transverse width of the image on the sensor of the camera in pixels can be read off by software available freely from the internet. By taking a photograph of the virtual image from two positions of the camera separated by a distance along the line of sight of the camera, we have determined the transverse width of the virtual image. From this we find the focal lengths of the lenses knowing the transverse width and the distance of the object from the lenses.

cs.CV↗

arXiv2022

Determination of the transverse width and distance of an object with a smartphone camera

A smartphone is a powerful learning aid in the hands of a large section of students around the world. The camera of the phone can be used for several learning purposes apart from its obvious purpose of photographing. If the focal length of the lens of the camera can be determined, several experiments in optics can be performed with it. In some recent works, the method of determination of the focal length has been discussed. When a real image of an object is formed by a lens of known focal length, one can determine either the distance or the transverse magnification of the object if the other is known. In this work we have shown that we can determine both the transverse size and the distance of an object, by photographing it from two positions, separated by a distance along the line of sight of the camera.

physics.ed-ph↗

arXiv2021

Determination of the refractive index of water and glass using smartphone cameras by estimating the apparent depth of an object

A smartphone camera can be used for measuring the width and distance of an object by taking its photograph. The focal length of the camera lens can be determined very accurately by finding the image width of an object on the camera sensor to micron level accuracy. The level of accuracy achieved with the help of camera sensors, allows us to determine the refractive index of water upto four significant digits by finding the apparent depth of an object immersed in it. We have also measured the refractive index of glass by the same method, using three glass slides of different thicknesses, the smallest being 1.2 mm.

physics.ed-ph↗