Leaf Electroscope Research Articles

Electrospun PAN-HNTs composite nanofiber membranes for efficient electrostatic capture of particulate matters

The fine particulate matter (PM) pollution has become a serious concern to public health. As the core part of PM air filters, high-performance electrostatic nanofiber membranes are urgently needed. However, the existing air filters remain challenging to further decrease the pressure drop to improve the wearer comfort. On the other hand, the rapidly disappearing static electricity of the existing electrostatic nanofiber inevitably gives rise to a relatively short service life. Here, we demonstrate a novel and enhanced electrostatic nanofiber membrane by introducing the halloysite nanotubes (HNTs) to the traditional electrospun PAN nanofiber membrane. The optimal PAN-HNTs nanofiber membrane shows a high removal efficiency of 99.54%, a low pressure drop of 39 Pa, and a high quality factor of 0.89 Pa−1. This greatly improved filtration performance can be attributed to the increased surface area and diameter of nanofiber after introducing the HNTs as additives with suitable doping concentrations. More importantly, compared with the pure PAN nanofiber membrane, the electrostatic capacity of the PAN-HNTs nanofiber membrane is significantly enhanced, which is confirmed by the leaf electroscope. After introducing the HNTs as additives, the surface of the PAN-HNTs nanofiber membrane becomes hydrophilic, which benefits for preventing foulants from attaching to the surface. We anticipate that the PAN-HNTs nanofibers as high-performance membrane air filters will bring great benefits to public health.

Dose Rate Measurement of X-rays emitted from Crookes Tube with Leaf Electroscope

Dose Rate Measurement of X-rays emitted from Crookes Tube with Leaf Electroscope

Demonstration of a Faraday Cage Using a Metal Leaf Electroscope

Ametal leaf electroscope has often been used for teaching electrostatics. For example, Fig. 1 is a very early one demonstrating electrostatic induction with a gold leaf electroscope. Alternatively we can charge the electroscope by touching a charged object to it. In both cases, induction or charging, the metal leaves push away from each other for a “Λ” shape.

An electronic electroscope for determining polarity of charge

In this study, we made a simple electronic electroscope called a ‘polarity detector’ which can determine the type of electric charge on any objects. We used the polarity detector in some student experiments in the physics laboratory. For example, when we applied a plastic rod to a piece of fabric made of wool, we could easily determine that the plastic rod was electrified with a negative electrical charge using the polarity detector. Similarly, we could show that a glass rod applied to a piece of silk fabric was electrified with a positive type of charge. However, when we carried out the same experiments with a metal leaf electroscope instead of the polarity detector, in both cases, the leaves of the electroscope were opened and gave the same response for plastic and glass rods. Thus, the electroscope with a metal leaf does not provide an idea of the type of electric charge on plastic or glass rods. Although this tool is made of cheap materials and is very simple, we have seen that it works quite well in the laboratory and contributes to the easy learning of static electricity. Therefore, we think it would be useful to use this simple instrument in the physics laboratory as an aid to metal–leaf electroscopy.

The structure of the capacitor and operating principle of a leaf electroscope

The structure of the capacitor and operating principle of a leaf electroscope

Three new simulations and games for teaching electrostatics and circuits: Craig’s “Metal Leaf Electroscope Simulator,” Blackman’s “Crack the Circuit,” and Kortemeyer’s “Kirchhoff’s Revenge”

<i>Three new simulations and games for teaching electrostatics and circuits: Craig’s “Metal Leaf Electroscope Simulator,” Blackman’s “Crack the Circuit,” and Kortemeyer’s “Kirchhoff’s Revenge”</i>

The Leaf Electroscope: A Take-Home Project of Unexpected Depth

The leaf electroscope is a common piece of demonstration equipment found in many high school and introductory college physics laboratories. Its simplicity allows a compelling demonstration of electrostatic forces, and its versatility makes it useful in the demonstration of a number of physical phenomena. The electroscope has a long history; a device for detecting net static charge using a rotating needle, the versorium, was described by Gilbert in De Magnete in 1600.1 The leaf electroscope was invented by Bennet and described in a letter published by the Royal Society in 1787.2 This paper will describe the use of the leaf electroscope as a build-at-home project in the second-semester introductory calculus-based physics class at the University of Arkansas.

セパレータを有する箔検電器の製作と診断用X線装置を用いた実験の提案

In order to use the practical training for beginners by means of a diagnostic X-ray, a leaf electroscope (which has a function to explain the ionization) was newly produced. The X-ray was introduced to the air in the electroscope having the electric charged leaf (the leaf was open at this time). The air irradiated by the X-ray was ionized, and then the produced ions or electrons were combined with charges on the leaf. As a result, the leaf was closed. In this way, experimenters can know the production and/or movement of charges by observing the conditions of the leaf. For the developed leaf electroscope, we added separators to divide the inner space into two regions; one is the irradiation area and the other is the space including the leaf. The separators have through-holes and/or a metallic mesh in order to create various conditions. In this paper, we described that different experimental results based on uses of the different separators were reflected in the ionization of the irradiated air and in the interaction of the charged particles. We summarized that the practical training by means of the developed leaf electroscope was valuable to educate beginners.

A New Type of Leaf Electroscope of Which the Unfolded Angle is 180°

A New Type of Leaf Electroscope of Which the Unfolded Angle is 180°

Mr. Nicholson's doubler: an 18th-century programmable charge amplifier

Abraham Bennet, the inventor of the leaf electroscope, devised a three-plate procedure for doubling electric charge. Like so many other manual processes in the 18th century it was ripe for deskilling by mechanisation, and it was William Nicholson who mechanised it. Here, the author describes a replica of Nicholson&apos;s doubler which he has constructed and the difficulties he encountered in making it perform in the manner described by Nicholon.

Nuclear medicine from Becquerel to the present.

During a period of a little over ninety years, the use of radioactive materials has moved from the discovery of natural radioactivity by Becquerel to the use of highly sophisticated equipment for in-house production of biologically important molecules labeled with radionuclides, for the measurement of body functions. Radiation detectors have progressed from photographic plates and the gold leaf electroscope to the routine use of improved scintillation detectors for imaging the three-dimensional distribution of radioactive materials in the body as a function of space and time. It is expected that future improvements will be along the line of instruments with better spatial resolution, contrast, and sensitivity. Advances in hardware and software will be more than matched by developments in radiopharmaceuticals, including the use of monoclonal antibodies and receptor mapping agents which promise the exquisite specificity and sensitivity of radioimmunoassay procedures.

Determining the capacitance of a leaf electroscope

Determining the capacitance of a leaf electroscope

Reports from the Commission of Experimental Apparatus : Leaf Electroscope

Reports from the Commission of Experimental Apparatus : Leaf Electroscope

An electronic gold leaf electroscope

An electronic gold leaf electroscope

Electrostatic charging by condensation

Continuing the correspondence initiated by Mr P.J. Soilleux in the May issue of Physics Bulletin (p. 201) and followed up in later issues, it may interest readers to learn that a still earlier experiment was performed in 1787 by the Rev. Abraham Bennet who invented the gold leaf electroscope.

Electrical Measurements in the Eighteenth Century

IN the Annals of Science, 1, No. 1, January 1936, Mr. W. Cameron Walker, of Minchenden School, London, gives an interesting historical account of the detection and estimation of electric charges in the eighteenth century, Perhaps in no other branch of science could he have found a better illustration that progress in science is conditioned by the invention and improvement of instruments. Up to the time of Volta, Bennet's familiar gold leaf electroscope was the most sensitive detector of electricity. Its invention marks the end of a period of evolution beginning with the time when the experimenter obtained electrical charges by simply rubbing pieces of amber, glass or sulphur on his coat. Boyle and Newton had in turn extended the observations of Gilbert concerning the attractive powers of electrified bodies, while von Guericke came very near to anticipating Du Fay in the recognition of two opposite states of electricity. But to Hauksbee, with whom the story of the eighteenth century begins, belongs the credit of the first systematic investigation of ‘electric effluvia’. He was surprised to notice that threads enclosed in an ‘uncharged’ globe of glass were immediately affected by the approach of a rubbed rod of sealing wax. But he makes no reference to the repulsion of the threads. For this new step we have to wait until twenty years later. In 1767, when describing a Leyden jar, Priestley writes that what electricians chiefly want to know is ‘how high a phial is charged’. Methods of measuring this were soon described by Lane and Henly. Then we come to the wonderfully accurate experiments of Cavendish and the evolution of the condensing electrometer by Volta the most skilful worker in this field. We think Mr. Walker has done well to direct attention to the valuable work done by eighteenth century electricians.

三島に於ける太陽紫外線に對する大氣透過率に就て

In this paper we report the seasonal change of the transmission coefficient of ultraviolet solar radiation observed at Misima over the period from September 1932 to November 1933. The instrument we used is the so-called “vital ray meter” made by the Tokyo Electric Company, consisting principally of cadmium photo-cell and aluminium leaf electroscope. Since the light we dealt with is not homogeneous, but covers the wavelengths ranginging from 0.29μ, to 0.32μ, the transmission coefficient has a meaning only in a sense of some mean. We define it as _??_ in the formula: where Isecz is the intensity observed, z being the zenith-distance of the sun, and I0 the intensity outside the earth's atmosphere. We determined I0 from the data of simultaneous observations made by Prof. R. Sekiguti on the summit of Mt. Fuji in June 1933 with our instrument and the standard cadmium cell, which had been in use there. The method of calculation is the one which was also suggested by him and is as follows. We calculate I0/Isecz by numerical integration for the value of ozone-depth, which is determined from the observation with the standard photo-cell, and then multiplying I0/Isecz by the value of Isecz, observed with our instrument, I0 is obtained. The transmission coefficient was found to be markedly dependent upon sec z, so, in order to investigate the seasonal variation, we constructed isopleth diagram with season as abscissa and sec z as ordinate. We see from this diagram that the transmission coefficient becomes maximum in November, December and January and minimum in June and July. This may be attributed to the corresponding variation of ozone and dust content in the upper atmosphere.

Cosmic rays — What physicists have learned about them

“Cosmic rays” is the name applied to the ultimate cause of that part of the ionization of the air that cannot be ascribed to any known agencies. In spite of this prosaic definition, however, seldom if ever has there been a subject of research in physics in which intrinsic importance and romantic associations so happily are combined. In view of the fundamental importance of cosmic ray research, in this article is given a review of studies made in this engrossing field from the time of early experiments with the gold leaf electroscope down to the present day of many and conflicting theories and speculations.

The Scattering of Fast Electrons by Metals. II. Polarization by Double Scattering at Right Angles

The first paper of this series discussed methods of counting fast electrons, a consideration of which has shown the need for further experiments looking for polarization of fast electrons. The present paper concerns a search for polarization by double scattering at right angles, using radium E as a source, and a sensitive gold leaf electroscope to detect the arrival of the scattered electrons, the slower electrons being eliminated from the experiment. A peculiar type of polarization appears, which can be described as follows, using the notation of previous papers. At moderate electron speeds the number counted in the configuration called 0\ifmmode^\circ\else\textdegree\fi{} is greater than the number counted at 180\ifmmode^\circ\else\textdegree\fi{}. This effect does not appear for very slow electrons. As the speed of the electrons approaches that of light, the above type of polarization persists, and another type appears, superposed upon the first; the number counted at 270\ifmmode^\circ\else\textdegree\fi{} becomes greater than the number counted at 90\ifmmode^\circ\else\textdegree\fi{}. Previous experiments of a similar nature, in which one or the other of the above effects appears, are discussed.

Experimental and Theoretical Studies in X-Ray Intensity Measurement

The paper describes experiments on the distribution of X rays in a water phantom under a variety of conditions. The quality of the radiations has been measured by determinations of the effective wave-length as measured by aluminium and copper absorption, while the maximum voltage on the tube has been measured spectrographically, using a simple spectrophotometer constructed for the purpose. Measurements have been made of the intensity of X-radiation at various depths and positions, using a small ionization chamber connected to a gold leaf electroscope. The relation between effective wave-length and percentage depth does is discussed and an attempt is made to find the relationship between the percentage depth dose and the size of the field. It is shown that the results are in agreement with a relationship of the form DPercnt; = Do + K′ [1−e−μa] where Do is the percentage depth dose with a very small field, a the radius of the field and μ the absorption coefficient of the radiation. Complete distribution exp...