This paper presents a high accuracy method to measure gravitational acceleration in an undergraduate

laboratory program. The experiment is based on water in a cylindrical vessel rotating about its

vertical axis at a constant speed. The water surface …

## Two activities with a simple model of the solar system: discovering Kepler’s 3rd law and investigating apparent motion of Venus

An astronomy ‘experiment’ composed of three parts is described in the article. Being given necessary

data a simple model of inner planets of the solar system is made in the first part with planets’

circular orbits using appropriate scale. In the seco…

## Reply to remarks of R Cross on ‘A comparative study of two types of ball-on-ball collision’

In this letter, I explain an error which was identified to me in my use of the equation ##IMG##

[http://ej.iop.org/images/0031-9120/53/1/016502/pedaa968fieqn001.gif] {$v_n=e^nv_0$} in the first

method of measuring the coefficient of restitution of tw…

## CD sundials

In this paper I present various equatorial sundial designs that use diffraction on a CD to display

time. The designs described in the paper include a transparent CD sundial equipped with a small

terrestrial globe. This sundial is compact, pedagogical…

## Remarks on ‘A comparative study of two types of ball-on-ball collision’

This comment addresses some points in the paper by White (2017 Phys Ed . 52 045013). Specifically,

we clarify the value for the coefficient of restitution, which we believe to be much lower than that

obtained by White.

## An impacting linear three body system

We study a system of three identical bodies that can move freely on a horizontal track. Initially

one body moves and two are at rest. The moving body impacts with one of the resting bodies which

then impacts with the third and so on. The impacts are …

## Understanding ‘human’ waves: exploiting the physics in a viral video

Waves are a relevant part of physics that students find difficult to grasp, even in those cases in

which wave propagation kinematics can be visualized. This may hinder a proper understanding of

sound, light or quantum physics phenomena that are expla…

## Asking the next generation: the implementation of pre-university students’ ideas about physics laboratory preparation exercises

It was planned to introduce online pre-laboratory session activities to a first-year undergraduate

physics laboratory course to encourage a minimum level of student preparation for experiments

outside the laboratory environment. A group of 16 and 17 …

## Teaching torque with 5E learning strategy: an off-center disk case

In this paper, five simple demonstrations with an off-center disk that can be easily constructed and

demonstrated in science class are described along with the 5E learning strategy. These

demonstrations can be used to help students develop an underst…

## Radiation sensors for medical, industrial and environmental applications: how to engage with schools and the general public

Radiation, radiation detection and radiation protection are topics in physics and its applications

which generate a wide interest in the public. This interest is either generated through medical

procedures, applications of nuclear energy or nuclear a…

## High powered rocketry: design, construction, and launching experience and analysis

In this study, the nuts and bolts of designing and building a high powered rocket have been

presented. A computer simulation program called RockSim was used to design the rocket. Simulation

results are consistent with time variations of altitude, vel…

## Melting ice

In this brief frontline, we want to describe the well-known fact that, when freshwater ice melts,

the freshwater liquid level does not change. In the Italian Ministerial programs, fluid statics is

introduced in the three years of middle school (stude…

## The kickstart of the age of the Earth race: revisiting the experiment of the Comte de Buffon at school

In this work, the first experiment ever done to determine the age of the Earth is revisited. The

benefits of its application at primary and secondary school levels are presented and discussed. In

particular, emphasis is placed on the advantage of fac…

## Demonstration of hydrostatic paradox with plastic bottles and LabQuest Vernier

This work focuses on the experimental demonstration of the hydrostatic paradox using simple tools in

the form of plastic bottles and plastic syringes with a thread. For the evaluation of the results

obtained the data logger Lab Quest Vernier was used…

## Informal physics learning from video games: a case study using gameplay videos

Researching informal gameplay can be challenging, since as soon as a formal study design is imposed,

it becomes neither casual nor self-motivated. As a case study of a non-invasive design, we analyze

publicly posted gameplay videos to assess the effe…

## A presentation of the black hole stretching effect

Black holes and the physics behind them is a fascinating topic for students of all levels. The

exotic conditions which prevail near a black hole should be discussed and presented to undergraduate

students in order to increase their interest in studyi…

## Variation of the friction coefficient for a cylinder rolling down an inclined board

A cylinder rolling down an inclined board is a commonly seen and interesting object to study and it

is also easy to experiment with and model. Following what has become a popular practice, we use

smartphones to measure the angular acceleration of a c…

## Heat convection at the density maximum point of water

Water exhibits a maximum in density at normal pressure at around 4° degree temperature. This paper

demonstrates that during cooling, at around 4 °C, the temperature remains constant for a while

because of heat exchange associated with convective curr…

## A useful demonstration of calculus in a physics high school laboratory

The real power of calculus is revealed when it is applied to actual physical problems. In this

paper, we present a calculus inspired physics experiment suitable for high school and undergraduate

programs. A model for the theory of the terminal veloci…

## Liquid oscillations in a U-tube

In hydrostatics, pressure measurement with U-gauges and their relationship to density is a

well-known experiment. Very little is studied or experimented with the dynamics of the movement of a

liquid in a U-tube probably due to its theoretical complex…

## A demonstration device for cosmic rays telescopes

We describe a hands-on accurate demonstrator for cosmic rays realized by six high school students.

The main aim is to show the relevance and the functioning of the principal parts of a cosmic ray

telescope (muon detector), with the help of two large …

## A discussion about ionising and non-ionising radiation and the critical issue of mobile phones

Electromagnetic radiation is one of the most important issues affecting peoples’ lives today. The

misunderstanding of students and the general population of the effects of electromagnetic radiation

is a problem which must be eliminated. Thus, a discu…

## Teaching the nature of physics through art: a new art of teaching

Science and art are traditionally represented as two disciplines with completely divergent goals,

methods, and public. It has been claimed that, if rightly addressed, science and art education could

mutually support each other. In this paper I propos…

## Measuring the coefficients of kinetic and rolling friction by exploring decaying mass-spring oscillations

A novel method of measuring the coefficients of kinetic and rolling friction is proposed. The method

is simple to implement and reliable. Samples of measurements and calculations are presented.

## Estimating the value of the inclination angle of the lunar plane to the ecliptic plane

Sky appears to our students as a vast volume surrounding the Earth. The most striking astronomical

events that they can witness in the sky are lunar phases and eclipses. However, eclipses do not

occur as often as full and new phases of the Moon. This…

## Learning to teach inquiry with ICT

Research has shown that the objectives for laboratory teaching—just as with other teaching

methods—are often not achieved and that many laboratory sessions are ineffective and yet expensive

in terms of pupil and teacher time, and facilities. There ar…

## Higgs potential and fundamental physics

Physics associated with the Higgs field potential is rich and interesting and deserves a concise

summary for a broader audience to appreciate the beauty and the challenges of this subject. We

discuss the role of the Higgs potential in particle physic…

## CPT invariance in classical electrodynamics

The transformation properties of classical electrodynamic variables under charge conjugation C ,

parity reversal P , and time inversion T are considered both for standard and atypical assumptions

for the nature of charge. We have shown that four dist…

## Why do aged fluorescent tubes flicker?

Our everyday experience of aged and defective fluorescent tubes or bulbs informs us that they may

flicker and emit a clicking sound while struggling to light up. In this article, the physical

mechanisms controlling the initial illumination of a funct…

## Tight-binding tunneling amplitude of an optical lattice

The particle in a periodic potential is an important topic in an undergraduate quantum mechanics

curriculum and a stepping stone on the way to more advanced topics, such as courses on interacting

electrons in crystalline solids, and graduate-level re…

## Langevin equation with time dependent linear force and periodic load force: stochastic resonance

The motion of a particle described by the Langevin equation with constant diffusion coefficient,

time dependent linear force ( ##IMG##

[http://ej.iop.org/images/0143-0807/38/6/065104/ejpaa8d54ieqn1.gif] {$\omega (1+\alpha \cos ({\omega

}_{1}t))x$} )…

## Using Galilean satellites’ mutual orbital events as an educational tool for studies of orbital dynamics

We present a methodology to analyse and interpret a set of telescopic observations of the mutual

orbital phenomena between Jupiter’s Galilean satellites (occultation and eclipses) as a practical

teaching tool for photometry and astrodynamic studies i…

## Great moments in kinetic theory: 150 years of Maxwell’s (other) equations

In 1867, just two years after laying the foundations of electromagnetism, J. Clerk Maxwell presented

a fundamental paper on kinetic gas theory, in which he described the evolution of the gas in terms

of certain ‘moments’ of its velocity distribution …

## Dynamics of damped oscillations: physical pendulum

The frictional force between a physical damped pendulum and the medium is usually assumed to be

proportional to the pendulum velocity. In this work, we investigate how the pendulum motion will be

affected when the drag force is modeled using power-la…

## Decomposition of the compound Atwood machine

Non-standard solving strategies for the compound Atwood machine problem have been proposed. The

present strategy is based on a very simple idea. Taking an Atwood machine and replacing one of its

bodies by another Atwood machine, we have a compound ma…

## Application of peer instruction in the laboratory task of measuring the effective mass of a spring

Peer instruction (PI) is an effective interactive approach to teaching and learning that has

principally been used to modify the experience of learning in traditional physics lecture settings.

This article further illustrates how the concept of PI ca…

## Locus of the apices of projectile trajectories under constant drag

Using the hodograph method, we present an analytical solution for projectile coplanar motion under

constant drag, parametrised by the velocity angle. We find the locus formed by the apices of the

projectile trajectories, and discuss its implementatio…

## The equally spaced energy levels of the quantum harmonic oscillator revisited: a back-to-front reconstruction of an n -body Hamiltonian

The ‘back-to-front’ derivation of the properties of the quantum harmonic oscillator (QHO), starting

with its equally spaced energy levels, is re-examined. A new derivation that exploits the natural

rotational symmetry of the QHO is proposed. The new …

## Transmission and reflection of a quantum particle incident upon potential drops

We consider the probabilities of transmission p T and reflection p R of a quantum particle incident

upon potential drops with significant qualitative differences. We look at a smooth potential drop

for which the potential and the derivative of the po…

## Software-aided discussion about classical picture of Mach–Zehnder interferometer

The Mach–Zehnder interferometer has played an important role both in quantum and classical physics

research over the years. In physics education, it has been used as a didactic tool for quantum

physics teaching, allowing fundamental concepts, such as…

## Indeterminacy of drag exerted on an arrow in free flight: arrow attitude and laminar-turbulent transition

The aerodynamic properties of an arrow (A/C/E; Easton) were investigated in an extension of our

previous work, in which the laminar-turbulent transition of the boundary layer on the arrow shaft

was found to take place in the Re number range of 1.2 × …

## Labatorials in introductory physics courses

Traditional lab sections in introductory physics courses at Mount Royal University were replaced by

a new style of lab called ‘labatorials’ developed by the Physics Education Development Group at the

University of Calgary. Using labatorials in introd…

## Focus on advanced optics—optical enlightenment

Description unavailable

## Uncertainty relations for a particle confined in a finite square well potential

In order to specify the uncertainty relation for a particle confined in a finite square well

potential we derived the standard deviation of momentum ##IMG##

[http://ej.iop.org/images/0143-0807/38/6/065402/ejpaa8417ieqn1.gif] {${\rm{\Delta }}p$} and t…

## An innovative experimental sequence on electromagnetic induction and eddy currents based on video analysis and cheap data acquisition

In this work, we present a coherent sequence of experiments on electromagnetic (EM) induction and

eddy currents, appropriate for university undergraduate students, based on a magnet falling through

a drilled aluminum disk. The sequence, leveraging on…

## Solving the linear inviscid shallow water equations in one dimension, with variable depth, using a recursion formula

When solving the linear inviscid shallow water equations with variable depth in one dimension using

finite differences, a tridiagonal system of equations must be solved. Here we present an approach,

which is more efficient than the commonly used nume…

## Mapping the magnetic field generated by a supercurrent in a ring of YBa 2 Cu 3 O 7− δ

We design and construct a device to map the magnetic field generated by a supercurrent in a

rectangular cross section ring of YBa 2 Cu 3 O 7− δ . For the measurements of the magnetic field, we

develop a Gaussmeter based on a commercial Hall effect se…

## Phasor representation for the nonlinear photoacoustic signal

In CO 2 laser-based photoacoustic (PA) systems, N 2 takes part in the generation of the PA signal.

This process causes the nonlinear relation of the photoacoustic signal to the CO 2 concentration.

This phenomenon can be explained simply using a phaso…

## Experimental investigation of an elastic pendulum

A mass on the end of a spring can oscillate vertically, horizontally or both at the same time.

Experimental observations are presented and simple explanations are given for the observed motion of

the mass, including the well known case where the freq…

## Interview: the buzz of discovery

Daven Armoogum is a teaching fellow at the Physics Department in UCL, where he motivates

undergraduate students in their practical work. David Richardson interviewed him to find out how his

passion for astronomy lead him to this position.

## Force, acceleration and velocity during trampoline jumps—a challenging assignment

Bouncing on a trampoline lets the jumper experience the interplay between weightlessness and large

forces on the body, as the motion changes between free fall and large acceleration in contact with

the trampoline bed. In this work, several groups of …

## Interview: Interview: the buzz of discovery

Daven Armoogum is a teaching fellow at the Physics Department in UCL, where he motivates

undergraduate students in their practical work. David Richardson interviewed him to find out how his

passion for astronomy lead him to this position.

## Aluminium and magnetism—the answer

In my article (Featonby 2017 Phys. Educ . 52 057001). A strong neodymium magnet is held over some

Japanese yen and some aluminum drinks can stay-tabs. The magnet is first withdrawn very slowly from

the piles. It is then raised quickly. The question w…

## Spinning top—the question

The motion of a spinning top can be mystifying at times until some basic principles are understood.

In this question the key to understanding what happens is the nature of the bottom tip of the top in

contact with the surface on which it spins.

## A wave optics approach to the theory of the Michelson–Morley experiment

A consistent classical wave optics approach to the theory of the Michelson–Morley experiment shows

that the original theory as applied by Michelson and Morley and others does not calculate the

optical paths of the two beams correctly, primarily bec…

## Multiple object, three-dimensional motion tracking using the Xbox Kinect sensor

In this article we discuss the capability of the Xbox Kinect sensor to acquire three-dimensional

motion data of multiple objects. Two experiments regarding fundamental features of Newtonian

mechanics are performed to test the tracking abilities of ou…

## Cusp singularity in mean field Ising model

The entropy of the Ising model in the mean field approximation is derived by the Hamilton–Jacobi

formalism. We consider a grand canonical ensemble with respect to the temperature and the external

magnetic field. A cusp arises at the critical point,…

## Symmetry and piezoelectricity: evaluation of α-quartz coefficients

Piezoelectric coefficients of α -quartz are derived from symmetry arguments based on Neumann’s

principle using three different methods: Fumi, Landau–Lifshitz and Royer–Dieulesaint. While the Fumi

method is tedious and the Landau–Lifshitz met…

## The most energy efficient way to charge the capacitor in a RC circuit

The voltage waveform that minimize the energy loss in the resistance when charging the capacitor in

a resistor–capacitor circuit is investigated using the calculus of variation. A linear voltage ramp

gives the best efficiency, which means a constan…

## Investigating the free-body diagram of a stationary object on an inclined plane using Apple Watch

In this study, we present an activity in which the free-body diagram of a real stationary object on

an inclined plane can be examined interactively. We use an Apple Watch and a few other materials

that can be accessed easily. Instead of an Apple Watc…

## A demonstration experiment for studying the properties of saturated vapor

The paper proposes an important demonstration experiment that can be used at secondary schools in

physics. The described experiment helps students learn the main concepts of the topic ‘saturated

vapor’, namely, evaporation, condensation, dynamic …

## White light Sagnac interferometer—a common (path) tale of light

White or polychromatic light sources are vastly abundant in nature and lie in our most basic

understanding of the theory of light, beginning from stars like our Sun and extending to every

common household light bulb or street lamp. In this paper, I p…

## In-class use of clickers and clicker tests improve learning and enable instant feedback and retests via automated grading

An audience response system (‘clickers’) was gradually incorporated into introductory physics

courses at Worcester Polytechnic Institute during the years 2011–14. Clickers were used in lectures,

as a means of preparing for labs, and for collect…

## An effective introduction to structural crystallography using 1D Gaussian atoms

The most important quantitative aspects of computational structural crystallography can be

introduced in a satisfactory way using 1D truncated and periodic Gaussian functions to represent the

atoms in a crystal lattice. This paper describes in detail…

## Corrigendum: ‘A full quantum analysis of the Stern–Gerlach experiment using the evolution operator method: analysing current issues in teaching quantum mechanics’

In this short Corrigendum we correct a little mistake (mainly in the sign) in the derivation of the

evolution of the wave function in the Stern–Gerlach experiment that appears in our published paper.

## Pressure in a tank due to water–ice phase transformation

Our aim is to show the surprising force of hydrogen bonds in ice. When a tank completely filled with

water is cooled, ice formation can generate a pressure which can cause its breaking. This phenomenon

is due to the fact that water has a higher densi…

## Exploration of task performance tests in a physics laboratory

In this article, we investigate the implementation of task performance tests in an undergraduate

physics laboratory. Two performance tests were carried out over two semesters using the task of

building a DC circuit. The first implementation in Spring…

## Atwood’s machine with a massive string

The dynamics of Atwood’s machine with a string of significant mass are described by the Lagrangian

formalism, providing an eloquent example of how the Lagrangian approach is a great deal simpler and

so much more expedient than the Newtonian treatment.

## Statistical mechanics of few-particle systems: exact results for two useful models

The statistical mechanics of small clusters ( n ∼ 10–50 elements) of harmonic oscillators and

two-level systems is studied exactly, following the microcanonical, canonical and grand canonical

formalisms. For clusters with several hundred partic…

## Benjamin Franklin and the dissectible capacitor: his observations might surprise you

Although he is best known as an American statesman, Benjamin Franklin also made important

contributions to electrical science in the mid-18th century. At the time, the Leyden jar, the first

capacitor, had just been invented, and Franklin performed ex…

## Searching for potentially habitable extra solar planets: a directed-study using real data from the NASA Kepler -Mission

What follows is a description of the procedure for a directed-study in which a student, guided by a

faculty member, attempted to identify potentially habitable exoplanets using actual data available

online from NASA’s Kepler Mission.

## Book: The Physics of Everyday Things

Description unavailable

## Graphs in kinematics—a need for adherence to principles of algebraic functions

Graphs in physics are central to the analysis of phenomena and to learning about a system’s

behavior. The ways students handle graphs are frequently researched. Students’ misconceptions are

highlighted, and methods of improvement suggested. While…

## A stroboscopic light source for experiments in mechanics

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…

## Teaching Einsteinian physics at schools: part 2, models and analogies for quantum physics

The Einstein-First project approaches the teaching of Einsteinian physics through the use of

physical models and analogies. This paper presents an approach to the teaching of quantum physics

which begins by emphasising the particle-nature of light th…

## Teaching Einsteinian physics at schools: part 1, models and analogies for relativity

The Einstein-First project aims to change the paradigm of school science teaching through the

introduction of modern Einsteinian concepts of space and time, gravity and quanta at an early age.

These concepts are rarely taught to school students despi…

## Which bulb is brighter? It depends on connection! Strategies for illuminating electrical concepts using light bulbs

In this paper, we examined teachers’ understanding of electrical concepts such as power, current and

potential difference based on how these concepts were applied to understand the relative brightness

seen in bulbs of different wattage under differ…

## Nuclear science and society: social inclusion through scientific education

This article presents a web-based educational project focused on the potential value of Information

and Communication Technology to enhance communication and education on nuclear science throughout

Brazil. The project is designed to provide trustwort…

## Using the Arduino with MakerPlot software for the display of electrical device characteristics

This paper shows how very simple circuitry attached to an Arduino microcontroller with MakerPlot

software can be used for the display of electrical characteristic curves of three commonly available

devices: an ohmic resistor, an LED, and a tungsten-f…

## Nuclear cartography: patterns in binding energies and subatomic structure

Nuclear masses and binding energies are some of the first nuclear properties met in high school

physics, and can be used to introduce radioactive decays, fusion, and fission. With relatively

little extension, they can also illustrate fundamental conc…

## Speed of transverse waves in a string revisited

In many introductory-level physics textbooks, the derivation of the formula for the speed of

transverse waves in a string is either omitted altogether or presented under physically overly

idealized assumptions about the shape of the considered wave p…

## Modern projection of the old electroscope for nuclear radiation quantitative work and demonstrations

Although quantitative measurements in radioactivity teaching and research are only believed to be

possible with high technology, early work in this area was fully accomplished with very simple

apparatus such as zinc sulphide screens and electroscopes…

## Surface charges and J H Poynting’s disquisitions on energy transfer in electrical circuits

In this paper we review applications given by J H Poynting (1884) on the transfer of electromagnetic

energy in DC circuits. These examples were strongly criticized by O Heaviside (1887). Heaviside

stated that Poynting had a misconception about the na…

## An environmental dose experiment

Several radiation sources worldwide contribute to the delivered dose to the human population. This

radiation also acts as a natural background when detecting radiation, for instance from radioactive

sources. In this work a medium-sized plastic scinti…

## Surface charges and J H Poynting’s disquisitions on energy transfer in electrical circuits

In this paper we review applications given by J H Poynting (1884) on the transfer of electromagnetic

energy in DC circuits. These examples were strongly criticized by O Heaviside (1887). Heaviside

stated that Poynting had a misconception about the na…

## An environmental dose experiment

Several radiation sources worldwide contribute to the delivered dose to the human population. This

radiation also acts as a natural background when detecting radiation, for instance from radioactive

sources. In this work a medium-sized plastic scinti…

## Downhill cycling symmetry breaking: how the rider foils experiment

In high-school teaching of mechanics, we deal, among other things, with the nature of static and

kinetic friction, forces that are proportional to the normal force. Under the influence of

frictional forces, a body moves down a rough sloped decline at…

## Radon measurement laboratories. An educational experience based on school and university cooperation

There is a growing interest in engaging students and the general public about the meaning and

objectives of doing science. When it is possible students can learn by actively engaging in the

practices of science, conducting investigations, sharing ide…

## Understanding the Doppler effect by analysing spectrograms of the sound of a passing vehicle

The purpose of this paper is to demonstrate how the Doppler effect can be analysed to deduce

information about a moving source of sound waves. Specifically, we find the speed of a car and the

distance of its closest approach to an observer using soun…

## Free fall and the equivalence principle revisited

Free fall is commonly discussed as an example of the equivalence principle, in the context of a

homogeneous gravitational field, which is a reasonable approximation for small test masses falling

moderate distances. Newton’s law of gravity provides …

## Experimental confirmation of Lenz’s law

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…

## Some didactical suggestions for a deeper embedding of DC circuits into electromagnetism

Undergraduate students often encounter great difficulties in understanding Ohm’s law and electrical

circuits. Considering the widespread students’ beliefs and their common mistakes, as they come out

from the literature and our teaching experience…

## Experimental confirmation of Lenz’s law

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…

## Some didactical suggestions for a deeper embedding of DC circuits into electromagnetism

Undergraduate students often encounter great difficulties in understanding Ohm’s law and electrical

circuits. Considering the widespread students’ beliefs and their common mistakes, as they come out

from the literature and our teaching experience…

## A semi-analytical approach to black body radiation

We describe a semi-analytical method to calculate the total radiance received from a black body,

between two frequencies. As has been done before, the method takes advantage of the fact that the

solution simplifies with the use of polylogarithm funct…

## A semi-analytical approach to black body radiation

We describe a semi-analytical method to calculate the total radiance received from a black body,

between two frequencies. As has been done before, the method takes advantage of the fact that the

solution simplifies with the use of polylogarithm funct…

## Demonstration of acoustic resonances in a cylindrical cavity applying the photoacoustic technique

In this work we present some experiments which can be performed in college or on the first courses

of university to acquire knowledge about resonant acoustical phenomena in closed cavities in a

tangible way, through experiments based on the photoacou…

## A quantitative experiment on the fountain effect in superfluid helium

Superfluid helium, a state of matter existing at low temperatures, shows many remarkable properties.

One example is the so called fountain effect, where a heater can produce a jet of helium. This

converts heat into mechanical motion; a machine with n…

## Impact of mass gain, tailwind and age on the performance of Usain Bolt from Beijing 2008 to Rio 2016

Despite the impressiveness of the sprints run by Usain Bolt, the question naturally arises of why he

has not been able to break the 100 m sprint world record he set in Berlin (2009). In this paper, we

address such a query by considering Bolt’s cond…

## Visualisation of charge dynamics when water droplets move off a hydrophobic surface

The Kelvin water drop generator is often used for educational purposes to visualise how charge is

transferred when water drops separate from a solid. Here, we discuss an alternative and simpler

setup, which allows one to visualise the charge transfer…