Search

We propose a laboratory experiment on the quantitative study of the normal dispersion of light. A triangular isosceles prism made of flint glass TF3 is used as the object of study, and we describe a simple and affordable device for observing and photographing the dispersion spectrum on a smartphone. A possibility of the quantitative investigation of light dispersion is provided by using a modern miniature mercury lamp emitting a line spectrum of mercury vapour against the background of a solid spectrum of white light. The method of processing experimental results is stated.

For conducting laboratory experiments on Fresnel diffraction, the use of a simple point light source from an LED and the application of a modern smartphone for photographing the diffraction patterns are proposed. The developed devices allow the experiments to be carried out under normal laboratory lighting.

To study the absorption of ultrasound in plexiglas we propose to use gadgets that are available to each student: an ultrasound humidifier, a liquid crystal display of a pad, a polaroid analyzer, a digital camera, a multimeter with thermocouple, and a stopwatch. These devices allow us to visualize a region in plexiglas where ultrasound is absorbed and to observe development of this region in dynamics because of the application of polarized light. With the help of these devices we can study the dependence of the temperature of plexiglas in the region of the ultrasound absorption on time and obtain quantitative estimates of the intensity of the ultrasound.

A series of demonstration experiments devoted to the relativity of translational motion in inertial and non-inertial reference frames is proposed. We recommend a simple algorithm for the formation of the ability to transform coordinates, speeds and accelerations during the transition from one reference system to another system moving translationally relative to the first one. Stroboscopic photographs of an experiment are given. In this experiment, a ball flies after a shot from a platform moving along a straight line uniformly or having a constant acceleration.

We propose the use of a laptop with a program generator and a transistor power amplifier to control the frequency, duration and amplitude of the LED stroboscope flashes. Examples of the stroboscopic photographs are given.

We report a synthesis of a series of molecular compounds and coordination polymers of Zn2+, Mn2+ Cd2+, Eu3+, and Tb3+ with 4-allyl-2,3,5,6-tetrafluorobenzoic acid (4-Afb) anions and 1,10-phenanthroline with compositions [Zn(H2O)(phen)(4-Afb)2] (1), [Mn(H2O)(phen)(4-Afb)2]n·nH2O (2), [Cd(H2O)(phen)(4-Afb)2]n (3), [Cd(phen)(4-Afb)2]n (4), [Ln2(phen)2(4-Afb)6] (Ln = Eu 5Eu; Tb 5Tb). It is shown that the obtained cadmium coordination polymers have various compositions and structures, depending on crystallization conditions. The prepared compounds are characterized by single-crystal XRD, powder XRD, IR spectroscopy, and CHN analysis. Noncovalent interactions are analyzed using the Hirshfeld surface analysis. It is determined that the crystal packings is mainly stabilized by π⋯π, C–H⋯F, and C–F⋯π interactions. The photoluminescent properties of the 5Eu and 5Tb complexes are studied. It is shown that the structure-forming effects of non-covalent "arene–perfluoroarene" interactions can be possibly used for preorganizing reactive functional groups in the crystal. [ABSTRACT FROM AUTHOR]

The paper presents a series of experiments that demonstrate the phenomenon of electromagnetic induction. These make it possible to determine the direction of the induced current and so confirm Lenz's Law. The simple experiments can be reproduced in a school laboratory and can be recommended for students' project activity.

We propose to attach a small stroboscopic light source to a moving object and connect the source to a pulse generator with the help of insulated thin flexible multi-cored wires. Students can assemble such a device independently in a school laboratory. The device can be used to obtain trajectories with time marks in students' research projects in mechanics. In the paper we give an example of the application of stroboscopic photography in a demonstration experiment devoted to inertia.

This paper presents a simple electromagnetic generator meant for use in students' experiments. This apparatus provides realization of a series of experiments demonstrating the principles of electricity generation and the conversion of electricity to other forms of energy with practical application. The experiments can be reproduced in a school laboratory and can be recommended for students' project activity.

A physical pendulum with a magnetic load is proposed for comparison of linear and nonlinear oscillations. The magnetic load is repelled by permanent magnets which are disposed symmetrically relative to the load. It is established that positions of the pendulum and the magnets determine the dependence of restoring force on displacement of the load. The dependence can be both linear and nonlinear. The apparatus is equipped with a photoelectric transducer. The signal goes to a computer and is displayed on the monitor as the dependence of the oscillation period on its number. If the position of the pendulum is normal then the oscillations are approximately linear. If the pendulum is turned over then its oscillations become substantially nonlinear.

The fundamentals of classical mechanics are the foundation of more complicated and ingenious physical theories. Therefore, an educational experiment revealing to students the physical nature of mechanical phenomena is important. The effectiveness of this experiment manifoldly increases if students not only perform it by themselves, but also make the necessary appliances with their own hands. Such devices should be modern in order to elicit the students' interest, and very simple so that creating them does not require much time and effort. This paper proposes a device that can be used in the experimental study of the relativity of mechanical motion and in the investigation of the motion of the solid mass centre in the Earth's gravitational field. The device is a soft disc into which a power supply, a switch, a pulse generator and two coloured light emitting diodes are fixed, so that the mass centre of the device does not coincide with the geometrical centre of the disc. One of the diodes is placed in the mass centre, and the other is located at the edge of the disc. Several interesting examples are considered as the body mass centre moves along a parabola, a cycloid and a straight line.

Students receive a more complete conception of scientific cognition methods if they reproduce fundamentally important historical investigations on their own. Ohm's investigation realized in 1826 is one of these. This paper presents a simple and accessible experimental unit, in which Ohm's ideas are implemented with the help of modern means. The unit includes a differential copper/constantan thermocouple, a solenoid, a compass and a spirit lamp. Doing the experiment, students investigate the dependence of current on the electromotive force of the source, source resistance and load resistance.

Students form a more exact idea of the action of optical mirrors if they can observe the wave field being formed during reflection. For this purpose it is possible to organize model experiments with flexural waves propagating in thin elastic plates. The direct and round edges of the plates are used as models of plane, convex and concave mirrors. The wave source is a vertically located vibrator of a magnetostriction radiator. The wave field is visualized with light dry powder. In these experiments students determine the wavelength and the velocity of a flexural wave, measure the distance from a wave's source to the mirror model, calculate its radius of curvature and make sure that the formula of a mirror is correct.

Four new complexes [Ln(pfaa)3(H2O)2] n (Ln = Eu (1), Tb (2)) and [Ln2Cd2(pfaa)10 (phen)2(EtOH)2]·2MeCN (Ln = Eu (3), Tb (4), phen = 1,10-phenanthroline) based on pentaphorphenylacetic acid (Hpfaa) have been prepared and completely investigated. The structures of compounds 1 and 3 were studied by single crystal X-ray diffraction analysis: the isostructural complexes 1 and 2 represent 1D coordination polymer, while the isostructural complexes 3 and 4 are molecular compounds. Complexes 1–4 show strong lanthanide-centred luminescence, since the introduction of phenanthroline leads to a significant increase in the observed lifetime (τ obs) and photoluminescent quantum yield. New complexes of Eu3+ and Tb3+ with pentafluorophenylacetic acid have been studied. During synthesis under hydrothermal conditions, polymer structures are formed, while the introduction of phenanthroline and Cd2+ makes it possible to obtain molecular complexes. A change in the structure leads to significant changes in the luminescent properties. [ABSTRACT FROM AUTHOR]