Stellar tidal disruption events may create Jupiter-mass “spitballs”
What’s the universe made of?
How much of you lies among the stars? How are the elements that make up life distributed among stars and planets? As trippy as the questions seem, astronomers from the Sloan Digital Sky Survey (SDSS) announced today at the 229th meeting of the American…
Two–faced moon
Space Science Image of the Week: A global colour mosaic of Saturn’s moon Dione shows striking contrasts between its two faces
Femtosecond measurements of electric fields: from classical amplitudes to quantum fluctuations
Ultrabroadband electro-optic sampling is presented as an extremely sensitive technique to detect
electric field amplitudes in free space. The temporal resolution provided by few-femtosecond laser
pulses results in a bandwidth exceeding 100 THz, poten…
On the realization of quantum Fisher information
With special attention to the role of information theory in physical sciences we present analytical
results for the coordinate- and momentum-space Fisher information of some important one-dimensional
quantum systems which differ in spacing of their e…
Einstein’s sigh: hidden symmetry in Einstein’s derivation of the Lorentz transformation
‘Das hätte ich einfacher sagen können (I could have said that more simply).’ was Einstein’s sigh
when he had a chance to remark on his own derivation of the Lorentz transformation (LT) in the 1905
seminal paper. In fact, in a popular science …
Experiential learning in high energy physics: a survey of students at the LHC
More than 36 000 students and post-docs will be involved until 2025 in research at the Large Hadron
Collider (LHC) mainly through international collaborations. To what extent they value the skills
acquired? Do students expect that their learning expe…
Einstein’s sigh: hidden symmetry in Einstein’s derivation of the Lorentz transformation
‘Das hätte ich einfacher sagen können (I could have said that more simply).’ was Einstein’s sigh
when he had a chance to remark on his own derivation of the Lorentz transformation (LT) in the 1905
seminal paper. In fact, in a popular science …
Femtosecond measurements of electric fields: from classical amplitudes to quantum fluctuations
Ultrabroadband electro-optic sampling is presented as an extremely sensitive technique to detect
electric field amplitudes in free space. The temporal resolution provided by few-femtosecond laser
pulses results in a bandwidth exceeding 100 THz, poten…
Experiential learning in high energy physics: a survey of students at the LHC
More than 36 000 students and post-docs will be involved until 2025 in research at the Large Hadron
Collider (LHC) mainly through international collaborations. To what extent they value the skills
acquired? Do students expect that their learning expe…
On the realization of quantum Fisher information
With special attention to the role of information theory in physical sciences we present analytical
results for the coordinate- and momentum-space Fisher information of some important one-dimensional
quantum systems which differ in spacing of their e…
Black Holes Hide in Our Cosmic Backyard
Monster black holes sometimes lurk behind gas and dust, hiding from the gaze of most telescopes.
Black Holes Hide in Our Cosmic Backyard
Monster black holes sometimes lurk behind gas and dust, hiding from the gaze of most telescopes.
The Case of the ‘Missing Link’ Neutron Star
A mysterious neutron star has been caught behaving like two distinct objects — a radio pulsar and a magnetar — and could be important to understanding the evolution of these objects.
Your Home Planet, as Seen From Mars
From the most powerful telescope orbiting Mars comes a new view of Earth and its moon, showing continent-size detail on the planet and the relative size of the moon.
Your Home Planet, as Seen From Mars
From the most powerful telescope orbiting Mars comes a new view of Earth and its moon, showing continent-size detail on the planet and the relative size of the moon.
The Case of the ‘Missing Link’ Neutron Star
A mysterious neutron star has been caught behaving like two distinct objects — a radio pulsar and a magnetar — and could be important to understanding the evolution of these objects.
Interplay Between Adsorption and Hydrodynamics in Nanochannels: Towards Tunable Membranes
Author(s): Sela Samin and René van Roij
Calculations show that capillary forces affecting a fluid mixture flowing through a nanochannel could be used to separate the mixture.
[Phys. Rev. Lett. 118, 014502] Published Fri Jan 06, 2017
Interplay Between Adsorption and Hydrodynamics in Nanochannels: Towards Tunable Membranes
Author(s): Sela Samin and René van Roij
Calculations show that capillary forces affecting a fluid mixture flowing through a nanochannel could be used to separate the mixture.
[Phys. Rev. Lett. 118, 014502] Published Fri Jan 06, 2017
This neutron star splits its time between pulsar and magnetar
Puls … ag … netar?
Two stars will merge in 2022 and explode into red fury
Get ready for a big nova event.
How the Voyagers and Hubble work together to map the final frontier
Three of NASA’s longest lasting missions work together to explore what lies beyond the Sun’s reach.
Astronomers get their first look at a mysterious galaxy with an unknown past
Why settle for one ring when you can have two?
A chunk of interplanetary debris recently slammed into Mars and left this fresh crater and spray of ejecta
Small asteroids and chunks of cometary debris frequently slam into the surface of Mars, gouging out new craters. Thanks to a high resolution camera aboard NASA’s Mars Reconnaissance Orbiter, scientists can often spot such impacts relatively soon …
How Far Away is That Galaxy? Vast Catalog Has Answers
A team of researchers has compiled a special catalog to help astronomers figure out the true distances to tens of thousands of galaxies beyond our own Milky Way.
How Far Away is That Galaxy? Vast Catalog Has Answers
A team of researchers has compiled a special catalog to help astronomers figure out the true distances to tens of thousands of galaxies beyond our own Milky Way.
Giant Spin-Orbit Splitting in Inverted InAs/GaSb Double Quantum Wells
Author(s): Fabrizio Nichele, Morten Kjaergaard, Henri J. Suominen, Rafal Skolasinski, Michael Wimmer, Binh-Minh Nguyen, Andrey A. Kiselev, Wei Yi, Marko Sokolich, Michael J. Manfra, Fanming Qu, Arjan J. A. Beukman, Leo P. Kouwenhoven, and Charles M. Marcus
A pair of semiconductor quantum wells with an inverted band structure hosts electrons whose spins are almost all in the same quantum state.
[Phys. Rev. Lett. 118, 016801] Published Thu Jan 05, 2017
Anisotropic Invariance and the Distribution of Quantum Correlations
Author(s): Shuming Cheng and Michael J. W. Hall
Two newly-discovered invariant properties of three-qubit states provide a fundamental missing link between two-party and three-party quantum correlations.
[Phys. Rev. Lett. 118, 010401] Published Thu Jan 05, 2017
Matter-Wave–Optical-Wave Mixing-Induced Transparency and a Nonhyperbolic Matter-Wave Quasisoliton in Quantum Gases
Author(s): Yan Li, Chengjie Zhu, W. R. Garrett, E. W. Hagley, and L. Deng
A new induced transparency effect is predicted to occur when a collective mode is excited in a Bose-Einstein condensate via a Raman process.
[Phys. Rev. Lett. 118, 013901] Published Thu Jan 05, 2017
Exacerbating the Cosmological Constant Problem with Interacting Dark Energy Models
Author(s): M. C. David Marsh
A theoretical analysis suggests that interacting models of dark energy may be in tension with anthropic explanations of the cosmological constant based on theories with a finite number of vacua.
[Phys. Rev. Lett. 118, 011302] Published Thu Jan 05, 2017
Bose-Einstein Condensation of Long-Lifetime Polaritons in Thermal Equilibrium
Author(s): Yongbao Sun, Patrick Wen, Yoseob Yoon, Gangqiang Liu, Mark Steger, Loren N. Pfeiffer, Ken West, David W. Snoke, and Keith A. NelsonMaking use of improved microcavities, hybrid condensates of matter and light can be tuned to reach a thermal e…
Unified Time and Frequency Picture of Ultrafast Atomic Excitation in Strong Laser Fields
Author(s): H. Zimmermann, S. Patchkovskii, M. Ivanov, and U. EichmannA study describes tunneling and multi-photon regimes as manifestations of the same nonlinear process, viewed in time and frequency domains.[Phys. Rev. Lett. 118, 013003] Published Thu…
Giant Spin-Orbit Splitting in Inverted InAs/GaSb Double Quantum Wells
Author(s): Fabrizio Nichele, Morten Kjaergaard, Henri J. Suominen, Rafal Skolasinski, Michael Wimmer, Binh-Minh Nguyen, Andrey A. Kiselev, Wei Yi, Marko Sokolich, Michael J. Manfra, Fanming Qu, Arjan J. A. Beukman, Leo P. Kouwenhoven, and Charles M. Marcus
A pair of semiconductor quantum wells with an inverted band structure hosts electrons whose spins are almost all in the same quantum state.
[Phys. Rev. Lett. 118, 016801] Published Thu Jan 05, 2017
Bose-Einstein Condensation of Long-Lifetime Polaritons in Thermal Equilibrium
Author(s): Yongbao Sun, Patrick Wen, Yoseob Yoon, Gangqiang Liu, Mark Steger, Loren N. Pfeiffer, Ken West, David W. Snoke, and Keith A. NelsonMaking use of improved microcavities, hybrid condensates of matter and light can be tuned to reach a thermal e…
Exacerbating the Cosmological Constant Problem with Interacting Dark Energy Models
Author(s): M. C. David Marsh
A theoretical analysis suggests that interacting models of dark energy may be in tension with anthropic explanations of the cosmological constant based on theories with a finite number of vacua.
[Phys. Rev. Lett. 118, 011302] Published Thu Jan 05, 2017
Unified Time and Frequency Picture of Ultrafast Atomic Excitation in Strong Laser Fields
Author(s): H. Zimmermann, S. Patchkovskii, M. Ivanov, and U. EichmannA study describes tunneling and multi-photon regimes as manifestations of the same nonlinear process, viewed in time and frequency domains.[Phys. Rev. Lett. 118, 013003] Published Thu…
Anisotropic Invariance and the Distribution of Quantum Correlations
Author(s): Shuming Cheng and Michael J. W. Hall
Two newly-discovered invariant properties of three-qubit states provide a fundamental missing link between two-party and three-party quantum correlations.
[Phys. Rev. Lett. 118, 010401] Published Thu Jan 05, 2017
Matter-Wave–Optical-Wave Mixing-Induced Transparency and a Nonhyperbolic Matter-Wave Quasisoliton in Quantum Gases
Author(s): Yan Li, Chengjie Zhu, W. R. Garrett, E. W. Hagley, and L. Deng
A new induced transparency effect is predicted to occur when a collective mode is excited in a Bose-Einstein condensate via a Raman process.
[Phys. Rev. Lett. 118, 013901] Published Thu Jan 05, 2017
Lowell Observatory to renovate Tombaugh’s Pluto telescope
The 1920’s era scope will be cleaned and repaired to return to tiptop shape
How NASA uses a common amateur astronomy technique to make huge discoveries
The Chandra deep field manages to look back to the edge of the visible universe using image stacking.
I’ll have a cosmo
By combining science with a few stellar brews, Astronomy on Tap has become a hit.
PALFA Survey discovers two intermittent pulsars
Now you see them, now you don’t
The year ahead
After an exciting 2016, ESA has a busy year in store
NASA Selects Two Missions to Explore the Early Solar System
NASA has selected two missions that have the potential to open new windows on one of the earliest eras in the history of our solar system – a time less than 10 million years after the birth of our sun.
Experimental Evidence for Sign Reversal of the Hall Coefficient in Three-Dimensional Metamaterials
Author(s): Christian Kern, Muamer Kadic, and Martin Wegener
A metamaterial that looks like chainmail has a Hall coefficient whose sign is flipped compared to the material it’s made from.
[Phys. Rev. Lett. 118, 016601] Published Wed Jan 04, 2017
Experimental Evidence for Sign Reversal of the Hall Coefficient in Three-Dimensional Metamaterials
Author(s): Christian Kern, Muamer Kadic, and Martin Wegener
A metamaterial that looks like chainmail has a Hall coefficient whose sign is flipped compared to the material it’s made from.
[Phys. Rev. Lett. 118, 016601] Published Wed Jan 04, 2017
Exploring our solar system’s origins with two new NASA missions
NASA’s newest Discovery-class missions will teach us more about our solar system and its formation.
Exploring our solar system’s origins with two new NASA missions
NASA’s newest Discovery-class missions will teach us more about our solar system and its formation.
Exploring our solar system’s origins with two new NASA missions
NASA’s newest Discovery-class missions will teach us more about our solar system and its formation.
Exploring our solar system’s origins with two new NASA missions
NASA’s newest Discovery-class missions will teach us more about our solar system and its formation.
Fast radio bursts now a bit less mysterious
For as long as astronomers have known about Fast Radio Bursts (FRBs), they’ve been stumped. About a decade ago, researchers discovered in archived 2001 data an extremely fast — just a few milliseconds — burst of radio emissions. They&…
Fast radio bursts now a bit less mysterious
For as long as astronomers have known about Fast Radio Bursts (FRBs), they’ve been stumped. About a decade ago, researchers discovered in archived 2001 data an extremely fast — just a few milliseconds — burst of radio emissions. They&…
The Imaging X-ray Polarimetry Explorer joins NASA’s Explorers Program lineup
NASA’s latest Explorers mission will focus on black holes and neutron stars
Clean slate
Space Science Image of the Week: Will this network of interstellar filaments ever form stars?
Earth from Space
Join us on Tuesday, 3 January at 14:00 CET for an interview with ESA’s Bianca Hoersch and Francois Spoto from the Sentinel-2B cleanroom
Experimental Realization of a Thermal Squeezed State of Levitated Optomechanics
Author(s): Muddassar Rashid, Tommaso Tufarelli, James Bateman, Jamie Vovrosh, David Hempston, M. S. Kim, and Hendrik Ulbricht
Quickly oscillating between two trapping frequencies creates mechanical squeezing of the thermal motion of an optically levitated nanosphere.
[Phys. Rev. Lett. 117, 273601] Published Fri Dec 30, 2016
Time-Resolved Imaging of Negative Differential Resistance on the Atomic Scale
Author(s): Mohammad Rashidi, Marco Taucer, Isil Ozfidan, Erika Lloyd, Mohammad Koleini, Hatem Labidi, Jason L. Pitters, Joseph Maciejko, and Robert A. WolkowCurrent flowing through a single silicon atom can be made to decrease with increasing voltage, …
Experimental Realization of a Thermal Squeezed State of Levitated Optomechanics
Author(s): Muddassar Rashid, Tommaso Tufarelli, James Bateman, Jamie Vovrosh, David Hempston, M. S. Kim, and Hendrik Ulbricht
Quickly oscillating between two trapping frequencies creates mechanical squeezing of the thermal motion of an optically levitated nanosphere.
[Phys. Rev. Lett. 117, 273601] Published Fri Dec 30, 2016
Time-Resolved Imaging of Negative Differential Resistance on the Atomic Scale
Author(s): Mohammad Rashidi, Marco Taucer, Isil Ozfidan, Erika Lloyd, Mohammad Koleini, Hatem Labidi, Jason L. Pitters, Joseph Maciejko, and Robert A. WolkowCurrent flowing through a single silicon atom can be made to decrease with increasing voltage, …
NASA’s NEOWISE Mission Spies One Comet, Maybe Two
NASA’s NEOWISE mission has recently discovered some celestial objects traveling through our neighborhood, including one on the blurry line between asteroid and comet.
NASA’s NEOWISE Mission Spies One Comet, Maybe Two
NASA’s NEOWISE mission has recently discovered some celestial objects traveling through our neighborhood, including one on the blurry line between asteroid and comet.
Weaving Knotted Vector Fields with Tunable Helicity
Author(s): Hridesh Kedia, David Foster, Mark R. Dennis, and William T. M. Irvine
A prediction of divergence-free knotted vector fields from complex scalar fields has consequences for studies of magnetic fields in complex patterns.
[Phys. Rev. Lett. 117, 274501] Published Thu Dec 29, 2016
Colloidal Surfaces with Boundaries, Apex Boojums, and Nested Elastic Self-Assembly of Nematic Colloids
Author(s): Sungoh Park, Qingkun Liu, and Ivan I. Smalyukh
Whether topological defects form when a disk-shaped particle is placed in a liquid-crystal bath depends on the thickness of the particle.
[Phys. Rev. Lett. 117, 277801] Published Thu Dec 29, 2016
Colloidal Surfaces with Boundaries, Apex Boojums, and Nested Elastic Self-Assembly of Nematic Colloids
Author(s): Sungoh Park, Qingkun Liu, and Ivan I. Smalyukh
Whether topological defects form when a disk-shaped particle is placed in a liquid-crystal bath depends on the thickness of the particle.
[Phys. Rev. Lett. 117, 277801] Published Thu Dec 29, 2016
Weaving Knotted Vector Fields with Tunable Helicity
Author(s): Hridesh Kedia, David Foster, Mark R. Dennis, and William T. M. Irvine
A prediction of divergence-free knotted vector fields from complex scalar fields has consequences for studies of magnetic fields in complex patterns.
[Phys. Rev. Lett. 117, 274501] Published Thu Dec 29, 2016
This researcher wants to initiate contact with Proxima Centauri b
The exoplanet next door could soon get an out-of-this-world radio broadcast.
Lift crisis of a spinning table tennis ball
The aerodynamic properties of a spinning table tennis ball were investigated using flight
experiments. Using high-speed video cameras, the trajectory and rotation of an official ball
(Nittaku 3-Star Premium), which was launched by a three rotor machine, were recorded. The drag and
lift coefficients ( C D and C L ) were determined by analysing the video images. The measurements
covered the speed and rotation range of typical table tennis shots in the form of the Reynolds
number ( Re ) and dimensionless spin rate ( SP ), i.e. 3.0 × 10 4 < Re < 9.0 × 10 4 and0 < SP
< 1.0, and C D and C L were obtained as functions of Re and SP . We determined that the lift
coefficient C L is not a monotonically increasing function of SP . A deep valley of C L was found
around SP = 0.5, and the lift force exerted …
Flow visualisation of downhill skiers using the lattice Boltzmann method
In downhill alpine skiing, skiers often exceed speeds of 120 km h −1 , with air resistance
substantially affecting the overall race times. To date, studies on air resistance in alpine skiing
have used wind tunnels and actual skiers to examine the r…
Developing and validating a conceptual survey to assess introductory physics students’ understanding of magnetism
Development of validated physics surveys on various topics is important for investigating the extent
to which students master those concepts after traditional instruction and for assessing innovative
curricula and pedagogies that can improve student …
Developing and validating a conceptual survey to assess introductory physics students’ understanding of magnetism
Development of validated physics surveys on various topics is important for investigating the extent
to which students master those concepts after traditional instruction and for assessing innovative
curricula and pedagogies that can improve student …
Lift crisis of a spinning table tennis ball
The aerodynamic properties of a spinning table tennis ball were investigated using flight
experiments. Using high-speed video cameras, the trajectory and rotation of an official ball
(Nittaku 3-Star Premium), which was launched by a three rotor machine, were recorded. The drag and
lift coefficients ( C D and C L ) were determined by analysing the video images. The measurements
covered the speed and rotation range of typical table tennis shots in the form of the Reynolds
number ( Re ) and dimensionless spin rate ( SP ), i.e. 3.0 × 10 4 < Re < 9.0 × 10 4 and0 < SP
< 1.0, and C D and C L were obtained as functions of Re and SP . We determined that the lift
coefficient C L is not a monotonically increasing function of SP . A deep valley of C L was found
around SP = 0.5, and the lift force exerted …
Flow visualisation of downhill skiers using the lattice Boltzmann method
In downhill alpine skiing, skiers often exceed speeds of 120 km h −1 , with air resistance
substantially affecting the overall race times. To date, studies on air resistance in alpine skiing
have used wind tunnels and actual skiers to examine the r…
Orbiter Recovering from Precautionary Pause in Activity
NASA’s Mars Odyssey orbiter, which has been in service at Mars since October 2001, put itself into safe mode — a protective standby status — on Dec. 26, while remaining in communication with Earth.
Orbiter Recovering from Precautionary Pause in Activity
NASA’s Mars Odyssey orbiter, which has been in service at Mars since October 2001, put itself into safe mode — a protective standby status — on Dec. 26, while remaining in communication with Earth.
Coherence Times of Bose-Einstein Condensates beyond the Shot-Noise Limit via Superfluid Shielding
Author(s): William Cody Burton, Colin J. Kennedy, Woo Chang Chung, Samarth Vadia, Wenlan Chen, and Wolfgang KetterleSeparated Bose-Einstein condensates can be shielded from external forces if immersed in a superfluid bath.[Phys. Rev. Lett. 117, 275301]…
Coherence Times of Bose-Einstein Condensates beyond the Shot-Noise Limit via Superfluid Shielding
Author(s): William Cody Burton, Colin J. Kennedy, Woo Chang Chung, Samarth Vadia, Wenlan Chen, and Wolfgang KetterleSeparated Bose-Einstein condensates can be shielded from external forces if immersed in a superfluid bath.[Phys. Rev. Lett. 117, 275301]…
This is astronaut Piers Sellers’ last message before his death
The UK-born astronaut and climate scientist recorded a final message for the global community before his death.
Anionic Hydrogen Cluster Ions as a New Form of Condensed Hydrogen
Author(s): Michael Renzler, Martin Kuhn, Andreas Mauracher, Albrecht Lindinger, Paul Scheier, and Andrew M. Ellis
Negatively charged hydrogen ion clusters—consisting of five or more hydrogen atoms—have been observed for the first time.
[Phys. Rev. Lett. 117, 273001] Published Tue Dec 27, 2016
Anionic Hydrogen Cluster Ions as a New Form of Condensed Hydrogen
Author(s): Michael Renzler, Martin Kuhn, Andreas Mauracher, Albrecht Lindinger, Paul Scheier, and Andrew M. Ellis
Negatively charged hydrogen ion clusters—consisting of five or more hydrogen atoms—have been observed for the first time.
[Phys. Rev. Lett. 117, 273001] Published Tue Dec 27, 2016
Pioneering physicist Vera Rubin dies at age 88
Rubin confirmed the existence of dark matter while fighting against entrenched sexism.
Once upon a time…
A feature-length compilation of the amazing adventures of Rosetta and Philae
Tian Shan
Earth observation image of the week: a Sentinel-2 false-colour image of China’s Tian Shan mountains, also featured on the Earth from Space video programme
The Moon
Visit ESA’s updated interactive guide to learn more about the why and how of lunar exploration
Axiomatic Relation between Thermodynamic and Information-Theoretic Entropies
Author(s): Mirjam Weilenmann, Lea Kraemer, Philippe Faist, and Renato RennerTwo notions of entropy are connected using a method reliant on basic properties common to both systems.[Phys. Rev. Lett. 117, 260601] Published Thu Dec 22, 2016
Axiomatic Relation between Thermodynamic and Information-Theoretic Entropies
Author(s): Mirjam Weilenmann, Lea Kraemer, Philippe Faist, and Renato RennerTwo notions of entropy are connected using a method reliant on basic properties common to both systems.[Phys. Rev. Lett. 117, 260601] Published Thu Dec 22, 2016
Earth from Space
Join us Friday, 23 December, at 10:00 CET for the ‘Earth from Space’ video programme. This week we explore China’s Tian Shan mountains
From outer space to inner eye
Contact lenses, spectacles and eye implants are now being made more accurately thanks to research instruments flying on the International Space Station.
From outer space to inner eye
Contact lenses, spectacles and eye implants are now being made more accurately thanks to research instruments flying on the International Space Station.
When astronauts ‘saved’ the worst year in American history (not 2016)
You know it’s been tough times when a Dumpster fire is the meme of the year. Indeed, 2016 has been rough: pop culture icons died, police and activists squared off in major cities, we survived a cutthroat presidential election, Syria burned, terro…
Year in images
Our year through the lens:a selection of our favourite images for 2016
An undergraduate laboratory experiment for measuring ε 0 , μ 0 and speed of light c with do-it-yourself catastrophe machines: electrostatic and magnetostatic pendula
An experimental set-up for electrostatic measurement of ##IMG##
[http://ej.iop.org/images/0143-0807/38/2/025203/ejpaa50c7ieqn1.gif] {${\varepsilon }_{0}$} ,
separate magnetostatic measurement of ##IMG##
[http://ej.iop.org/images/0143-0807/38/2/02520…
Influence of initial velocity on trajectories of a charged particle in uniform crossed electric and magnetic fields
Magnetic and electric fields can cause a charged particle to form interesting trajectories. In
general, each trajectory is discussed separately in university physics textbooks for undergraduate
students. In this work, a solution of a charged particle…
The paradoxical zero reflection at zero energy
Usually, the reflection probability R ( E ) of a particle of zero energy incident on a potential
which converges to zero asymptotically is found to be 1: ##IMG##
[http://ej.iop.org/images/0143-0807/38/2/025401/ejpaa4f96ieqn1.gif] {$R(0)=1$} . But ear…
Experiment and mathematical model for the heat transfer in water around 4 °C
Water, which is the habitat for a variety of living creatures, has a maximum density at 4.0 °C. This
crucial property is considered to play a very important role in the biology of a lake and also has a
close relationship with the areas of environmen…
Determining the efficiency of optical sources using a smartphone’s ambient light sensor
This work reports the use of a smartphone’s ambient light sensor as a valuable tool to study and
characterize the efficiency of an optical source. Here, we have measured both luminous efficacy and
efficiency of several optical sources (incandescent…
An undergraduate laboratory experiment for measuring ε 0 , μ 0 and speed of light c with do-it-yourself catastrophe machines: electrostatic and magnetostatic pendula
An experimental set-up for electrostatic measurement of ##IMG##
[http://ej.iop.org/images/0143-0807/38/2/025203/ejpaa50c7ieqn1.gif] {${\varepsilon }_{0}$} ,
separate magnetostatic measurement of ##IMG##
[http://ej.iop.org/images/0143-0807/38/2/02520…
Determining the efficiency of optical sources using a smartphone’s ambient light sensor
This work reports the use of a smartphone’s ambient light sensor as a valuable tool to study and
characterize the efficiency of an optical source. Here, we have measured both luminous efficacy and
efficiency of several optical sources (incandescent…
The paradoxical zero reflection at zero energy
Usually, the reflection probability R ( E ) of a particle of zero energy incident on a potential
which converges to zero asymptotically is found to be 1: ##IMG##
[http://ej.iop.org/images/0143-0807/38/2/025401/ejpaa4f96ieqn1.gif] {$R(0)=1$} . But ear…
Influence of initial velocity on trajectories of a charged particle in uniform crossed electric and magnetic fields
Magnetic and electric fields can cause a charged particle to form interesting trajectories. In
general, each trajectory is discussed separately in university physics textbooks for undergraduate
students. In this work, a solution of a charged particle…
Experiment and mathematical model for the heat transfer in water around 4 °C
Water, which is the habitat for a variety of living creatures, has a maximum density at 4.0 °C. This
crucial property is considered to play a very important role in the biology of a lake and also has a
close relationship with the areas of environmen…