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Talha's Physics Academy

Talha's Physics Academy is an exploration environment for concepts in physics which employs free Physics Books and other linking strategies to facilitate smooth navigationThe entire environment is interconnected with thousands of links, reminiscent of a neural network.

Talha's Physics Academy

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Talha's Physics Academy

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Talha's Physics Academy

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Geometry and Astronomy-Helge Kragh

Pre-Einstein Speculations of Non-Euclidean Space

Nikola Tesla 's Books

            (With spacial references to his work poly phase current and high potential lightning)

Adding more books soon....

Prodigal Genius : The Life of Nikola Tesla—Inventor Extraordinary 
John J. O'Neill, 1943

Lightning in His Hand : The Life Story of Nikola Tesla
Inez Hunt and Wanetta W. Draper

Tesla — Man Out of Time
Margaret Cheney

Wizard — The Life and Times of Nikola Tesla
Mark Seifer

Nikola Tesla — A Spark of Genius
Carol Dommermuth-Costa

Nikola Tesla — Correspondence with RelativesNikola Tesla

Nikola Tesla Correspondence — Microfilm Prints
Nikola Tesla

Tesla — The Lost Inventions
George Trinkaus

Nikola Tesla's Residences, Laboratories, and Offices
Leland I. Anderson

Dr. Nikola Tesla Bibliography
Leland Anderson & John Ratzlaff

Nikola Tesla Museum  

The Orders From Nikola Tesla Legacy  
Zorica Civric

Tesla — The Modern SorcererA biographical novel Daniel Blair Stewart

TESLA  Master of Lightning (hardcover, new)
Margaret Cheney & Robert Uth

Atlas Shrugged
Ayn Rand

Nikola Tesla — Genius Who Lit The World - 
Tesla Memorial Society; Ljubo Vujovic

Collected Articles of Nikola Tesla, Volume 1 --
Gary Peterson, Editor

Collected Articles of Nikola Tesla, Volume 2 --
Gary Peterson, Editor

Collected Articles of Nikola Tesla, Volume 3 --
Gary Peterson, Editor

Collected Articles of Nikola Tesla, Volume 4 --
Gary Peterson, Editor

An introduction to fluid dynamics - G.K. Batchelor

The Hidden Reality - Brian Greene

Parallel Universes and the Deep Laws of cosmos

Dictionary of Physics : S to Z


scalar a physical quantity that has magnitude but not direction
scintillation flashes of light arising from the impact of high-energy particles
(alpha particles) on a crystalline material
second the unit of time
secondary the output winding of a transformer
semiconductor a material in which the resistance decreases as its temperature
rises; its resistivity is higher than that of a conductor but lower
than that of a resistor
semiconductor, n-type a semiconductor in which 1 atom in a hundred thousand has
been replaced by an element with 1 more electron than the base
semiconductor, p-type a semiconductor in which 1 atom in a hundred thousand has
been replaced by an element with 1 less electron than the base
series circuit a circuit in which the components form a single conducting path
shell burning a phase in a star’s life during which the fusion processes occur in
a hot shell around an inert core that has not yet reached a high
enough temperature for the next fusion process to start
shock wave a wavefront produced by a source moving faster than the wave
speed (e.g. speed of sound)
significant figures the digits in a number that are known with certainty plus the first
digit that is uncertain
simple harmonic motion motion in which the force and acceleration are directed towards
the equilibrium position
Snell’s law the relation between the angles of incidence and refraction and
the refractive index when a light ray travels from one material
into another
solar cycle solar activity, as measured by sunspots, has a period of 11 years
solar system the system of planets, asteroids and comets orbiting the Sun
solar wind the stream of particles ejected from the Sun
solenoid a long coil of conducting wire
solstice the two days in the year when the Sun rises at its most northerly
and southerly points on the eastern horizon, i.e. midsummer and
sonar the use of sound waves to detect and estimate the range of
submerged objects
sound waves longitudinal waves of compression and rarefaction
spark chamber a means of imaging particle tracks using the ionisation of gas
between stacks of high voltage plates
specific impulse the ratio of the thrust to the rate of weight ejected;
I = thrust/(g Äm/Ät)
spectra, absorption continuum spectra showing dark absorption lines at wavelengths
where energy has been absorbed by a cool intervening gas
spectra, emission spectra in which bright emission lines are observed from highly
excited gas atoms
spectral type stellar classification based on the absorption features seen in the
blue in stellar spectra: OBAFGKMRNS
spectrograph an instrument for observing and recording spectra
spectrometer an instrument which splits light into its component wavelengths.
spectroscopic parallax the derivation of a star’s distance by using its spectral type to
estimate its absolute magnitude
speed distance travelled per unit time
spiral galaxy a galaxy that shows a nuclear bulge and a spiral disc structure
split ring commutator a commutator which is split into two segments allowing the
generation of DC power
SQUID superconducting quantum interface device: a device capable of
measuring extremely small magnetic fields
standing wave the resultant wave from two wave trains of equal amplitude,
wavelength and frequency travelling in opposite directions
through the same medium
star cluster, globular a cluster of stars which formed together and now appear to form
a compact spherical system
star cluster, open a cluster of stars which formed together and now appear as a
loosely bound system, e.g. the Pleiades
stator the fixed part of an electrical motor or generator
Stephan’s law the relationship between total power radiated by a black body
and its temperature and surface area L = sAT 4
stratosphere the layer of the Earth’s atmosphere at an altitude of between
12 km and 50 km
stroboscope a device that produces regular flashes of light
strong force the interaction which binds quarks to form neutrons and
protons; the strong force acts only between quarks
Sun our nearest star
sunspot a dark region that is cooler than the surrounding photosphere
supercluster a cluster of galaxy clusters
superconductor a conductor with almost zero resistance at low temperatures
supergiant a star with a radius several hundred times that of main sequence
stars with similar temperature
 supernova the final explosive stage of evolution of a massive star that has a
core of iron
superposition the combination of two or more waves to produce a resultant
synchrotron radiation electromagnetic radiation emitted by electrons moving at close to
the speed of light in strong magnetic fields
synchrotron a machine for accelerating particles to high energies
temperature a physical quantity of matter related to the average kinetic energy
of its particles


terminal velocity the constant velocity reached by a body falling through a fluid
when the frictional resistance equals the gravitational force
tesla the metric unit of magnetic field strength
thermionic devices, valves an electronic switch in which electron flow from a hot filament to
the anode is controlled by an intermediate, charged grid
thermosphere the region of the Earth’s atmosphere immediately above the
three degree background background radiation from the Big Bang now cooled to 3 K and
observable at millimetre wavelengths
thrust force developed by rocket motors
time a fundamental unit of measurement related to our perception of
change. Time passes!
time dilation the relativistic effect whereby the time measured by a moving and
a stationary observer differ
topography computer reconstruction of a section through an object
torque the product of a force times its lever arm
torsional wave a wave in which the particles twist backward and forward around
the direction of motion of the wave
total internal reflection when light travels from a region of high optical density to one
with a lower optical density at high angles of incidence it will be
totally reflected back into the material of high optical density
transducer (PZT) a device which converts electrical power into ultrasonic waves
transformer an electronic device that allows changes of voltage levels
transformer, step down an electrical device that converts high voltages across the
primary coils to lower voltages across the secondary coils
transformer, step up an electrical device that converts low voltages across the primary
coils to higher voltages across the secondary coils
transistor an electronic semiconductor switch which is based on p- and ntype
materials in a p-n-p configuration
transmutation the conversion of one element or nucleus into another
transverse wave a wave in which the particles move perpendicular to the direction
of the waves of propagation
troposphere the lowest layer of the Earth’s atmosphere to an altitude of 12 km
in which most of the weather systems are found
trough a region of downward displacement in a transverse wave


UHF ultra high frequency radio waves
ultrasound sound waves with frequencies above about 0.5 MHz
ultraviolet light electromagnetic radiation of higher frequency (shorter
wavelength) than visible light
unified field theory a theory that explains the effects of all four fundamental forces as
the manifestation of single field
units, imperial British units of measurement, e.g. pound, gallon, foot
Units, Système French system of units, now recognised internationally,
International d’Unités e.g. kilo, litre, metre
universe, closed a universe that contains sufficient matter to collapse back onto
universe, flat a universe which will gradually slow its expansion until it stops
universe, open a universe which will continue to expand forever


valence band the energy band in a solid in which the outermost valence
electrons are found
Van Allen radiation belts two regions at between 1000 km and 5000 km and 15 000 km and
25 000 km in which charged particles from the solar wind
become trapped
Van de Graaff generator a particle accelerator that transfers charge to an insulating sphere
by means of a moving belt made of an insulating material
vector dot product the result of vector multiplication, e.g. A.B. |A| |B| cosè
vector a quantity that has both a magnitude and a direction
velocity the time rate of change of displacement
VHF very high frequency radio waves
volt the unit of potential difference; the potential energy per unit
volt, electron the energy required to move an electron through a potential
difference of 1 volt
Voyager two spacecraft which flew by the giant gas planets, passing
Jupiter (1979), Saturn (1981), Uranus (1986) and Neptune (1989)


watt the unit of power, one joule per second (J s–1)
wave equation an equation expressing the amplitude of a wave in terms of its
time and position
wave train a continuous wave disturbance
wave velocity the product of a wave’s frequency and wavelength
wave, wavelength the distance between wave crests or troughs
wave, compression a wave in which the particles vibrate along the direction in which
the wave travels; sound waves are compression waves
wavefront a line connecting all points on a wave crest that are oscillating
wavelength the distance between a point on a wave and the nearest point in
phase with it
weak force the fundamental force that is responsible for the change of
particles from one form to another, e.g. the decay of neutrons
into protons
weber the unit of magnetic flux
weight the gravitational force acting on a mass
Wein’s displacement law the relationship between the wavelength at which most
electromagnetic radiation is emitted and the temperature of the
emitting source
white dwarf a star of intermediate mass that has produced a planetary nebula
and can now no longer support nuclear fusion in its core, it
therefore cools by radiating energy away to space336
work function the minimum energy required to remove an electron from a
surface in the photoelectric effect
work the product of the displacement and the force in the direction of
the displacement


X-rays high energy electromagnetic radiation of high penetrating power
X-ray diffraction the crystalline structure of materials can be studied by looking at
the interference patterns produced by X-rays reflected from the
different crystal planes


Zeeman effect the energy levels of an atom split when the atom is in a strong
magnetic field. This splitting produces a splitting in the observed
spectral lines.

Dictionary of Physics : M to R


magnet, hard magnetic materials that do not lose their magnetism easily when
the source of magnetism is removed, e.g. steel
magnet, soft magnetic materials that are easy to magnetise but rapidly lose
their magnetism; these are often used in electromagnets, e.g. iron
magnetic field a region in which a magnetic force can be detected
magnetic flux the lines of flux in a region of a magnetic field
magnetic force a force due to the motion of a charged particle in a magnetic field
magnetic levitation the use of the force between two opposing magnets to lift a body
magnetic moment the small magnetic field produced by a spinning nucleus
magnetic poles the points (north, south) of maximum magnetic flux
magnetic resonance imaging the proton distribution in the body using strong
imaging (MRI) magnetic fields and radiofrequency signals
magnetopause the region separating the extended solar magnetic field (solar
wind) from the Earth’s magnetosphere
magnetosphere the region close to a planet that is dominated by its own
magnetic field rather than that of the Sun
main sequence that part of the Hertzsprung–Russell diagram in which stars are
burning hydrogen to helium in their cores
mass defect the difference between the mass of a nucleus and the sum of the
masses of its uncombined protons and neutrons
mass number the sum of the numbers of protons and neutrons in an atom
mass spectrograph an instrument that determines the mass of charged particles
mass unit, atomic one-twelfth of the mass of a carbon-12 atom (1.6605655 × 10–27 kg)
mass a fundamental physical quantity; the amount of matter
medical physics the application of physics to medical procedures, usually in
reference to therapy or diagnosis
medium a region where a wave is propagated
meson a sub-atomic particle with zero, positive or negative charges, and
a mass between that of a proton and an electron
metre the standard unit of length in the metric system
mesosphere the middle layer of the atmosphere between 50 and 85 km
Michelson-Morley the experiment which showed that an aether did not exist
microwaves electromagnetic waves with wavelengths between 1 mm and
30 cm
Milky Way Galaxy our own galaxy
mobile electrons electrons that are free to move and carry current within a
conductor or semiconductor
moderator a material used to slow down neutrons (e.g. graphite, heavy
moment a measure of the turning effect of a force about a pivot point
moment of inertia a measure of the way a body resists rotational acceleration by a
torque; the rotational equivalent of inertial mass
momentum the product of the mass and velocity of a moving object
monochromatic light light composed of a single wavelength
Morse code a system used in signalling and telegraphy which uses sequences
of short pulses or dots and longer dashes
motion, circular motion of a body in a circular path8
motor, AC a motor which is powered by AC current
motor,DC a motor which is powered by DC current
motor, induction an AC motor in which currents in the primary winding (stator)
induce currents and magnetic fields in the moving rotor,
producing rotation
M-scan a form of ultrasound display in which a sequence of sequential B
scans are displayed in a stack to show how structures vary with
mutual induction two conducting coils are arranged so that a change of current in
one induces an EMF in the other


neutral point a point in a magnetic, electric or gravitational field at which a
body experiences no net force
neutrino a fundamental particle that interacts weakly with matter
neutron star a small, high-density object composed of neutrons; it is the final
stage of a star of intermediate mass
neutron a neutral subatomic particle of mass 1.6749 × 10–27 kg
newton the metric unit of force
Newton’s laws of motion laws that describe how bodies interact through forces and which
link acceleration, force and mass
node a point of zero amplitude on a standing wave
normal (to a surface) a line drawn perpendicular to a surface at the point of incidence
normal force the reaction force that acts on a body at rest on a surface
north geographic pole the point in the northern hemisphere through which the Earth’s
axis of rotation passes
north magnetic pole a point on the Earth’s surface toward which the north-seeking
pole on a compass points
nova a ‘new star’ which suddenly becomes visible to the naked eye.
Usually an evolved binary star containing a white dwarf, which
brightens by ten million times due to the transfer of material
between the white dwarf and its companion.
nuclear magnetic a method of imaging protons in the body using strong magnetic
resonance (NMR) fields and radiofrequencies to alter their nuclear spin
nuclear precession the way the spin axis of a nucleus rotates when placed in a strong
magnetic field
nuclear radiation any high energy particles or electromagnetic radiation which is
produced when a nucleus decays
nuclear spin a characteristic associated with the angular momentum of a
nucleon a proton or neutron in the nucleus of an atom
nucleus the positively charged dense part of the atom composed of
protons and neutrons
nuclide a distinct atomic species of given mass and atomic number


ohm the metric unit of resistance, 1 volt per ampere
Ohm’s law the ratio of the voltage across a resistor to the current flowing
through it is a constant
Olbers’ paradox if the universe is infinite, the sky should be completely covered by
stars and should be dazzling bright at night
optical density an optically dense material is one with a large refractive index
optical path difference the difference in distances travelled by two rays or wavefronts
before they interfere
optical path length the distance travelled by a light ray or wavefront
oscillation vibration
oscilloscope equipment using a cathode ray tube to display rapidly varying
ozone layer an atmospheric layer in which a high concentration of ozone
absorbs solar ultraviolet radiation


pair production the production of a particle and antiparticle from a photon with
sufficient energy
parallax changes in the projected position of a nearby object on a distant
background (ruler), brought about by movement of the observer
parallel circuit an electric circuit that has two or more components providing
separate conducting paths for the current
parsec the distance at which the radius of the Earth’s orbit subtends 1
arc second
pendulum a body suspended so that it can swing to and fro about an axis
perigee the closest point to the Earth on an Earth satellite’s orbit
perihelion the closest point to the Sun on a planet’s orbit
period the time for a complete cycle
periodic motion any repeated pattern of motion
period–luminosity diagram the relationship between absolute magnitude (or luminosity) and
period of Cepheid variables
permanent magnet a material which maintains its magnetism when the source
inducing it is removed
PET scanner an imaging system which uses tomographic techniques to image
the distribution of beta-plus emitting radiopharmaceuticals in
the body
photodiode a semiconductor diode used in detecting light
photoelectric effect the emission of electrons by a metal when illuminated by light in
the ultraviolet to visible range
photoelectrons electrons emitted by a metal that has been illuminated by light in
the ultraviolet to visible range
photometry the measurement of the apparent magnitudes of stars
photomultiplier a detector in which emission from a photocathode followed by
amplification of secondary electrons in a dynode chain produces
a measurable current
photon a quantum or packet of light energy
photosphere the visible surface layer of the Sun, which has a temperature of
6000 K
physical laws concise, general statements about how nature is observed to
piezoelectric effect the expansion and contraction of a crystalline material when an
AC voltage is applied
pitch the tone associated with a sound of definite frequency
Planck’s constant (h) a fundamental constant in nature that relates energy to the
frequency of a photon
Planck’s law the basis of quantum theory: ‘the energy of electromagnetic
waves comes in indivisible packets or quanta. Each must be
absorbed or radiated as a whole’; E = hf
Planck’s radiation law an expression for the spectrum emitted by a black body
plane of polarisation the plane of vibration of a transverse wave
planet the following bodies which orbit the Sun: Mercury, Venus, Earth,
Mars, Jupiter, Saturn, Uranus, Neptune, Pluto
planetary nebula a shell of ionised gas ejected from a star in its late stages of
plasma an extremely hot gas consisting solely of positive ions and
negative electrons
polarised light light with vibrations in a single plane, perpendicular to the ray
polarising film a plastic material that will plane-polarise light
polychromatic light light composed of a broad range of wavelengths (colours)
positron a particle with the same mass as an electron but with positive
potential difference the work done per unit charge as the charge is moved between
two points in an electric field
potential energy energy that is stored in a system and can be released
potential energy, energy that is due to a body’s position in a gravitational field
potential energy, spring energy that is stored in the compression of a spring or elastic
power the rate of doing work; units watts (W) or joules per second (J s–1)
precession motion that results from the application of a torque to a rotating
pressure force per unit area
primary the input winding of a transformer
principle quantum number an integer number (n = 1, 2, 3 …) upon which the allowed energy
levels in an atom depend
proper motion an astronomical body’s own motion across the sky
proto-galaxy a galaxy in the process of just forming
proton a positively charged subatomic particle of mass 1.6726 × 10–27 kg
proton–proton cycle the nuclear process that converts hydrogen into helium in the
cores of stars with masses lower than about 5Mo
protostar a star which is in the process of gravitational collapse, but has not
yet begun to fuse hydrogen to helium
pulsar a rapidly spinning, compact star with strong magnetic fields,
which produces regular pulsed radio emission with periods from
a few seconds to milliseconds
pulse a single disturbance in a medium


quantum a discrete unit of energy; a small building block of matter, e.g. a
quantum of charge
quark a fundamental particle which is thought to form the building
blocks of protons, neutrons and other hadrons
quasar unresolved, starlike sources with large redshifts and hence at
large distances. These are now known to be galaxies with nuclear
regions hundreds of thousands of times brighter than normal.


radial velocity the velocity of a star towards or away from the observer
radian the unit of angular measurement, 2ð radians = 360°
radio frequency signal an electromagnetic wave with frequencies in the radio waveband
radio waves electromagnetic waves produced by an alternating current in a
radioactive decay when unstable nuclei split into less massive daughter nuclei and
energetic particles
radioactive decay series a sequence of radioactive decays in which a long-lived nucleus
(e.g. 232Th) decays by intermediate stages to a second long-lived
nucleus (208Pb)
radioactivity the spontaneous breakdown of a nucleus with emission of
particles and rays
radiography the use of X-rays to image body tissue
radioisotope an isotope of an element that is radioactive
radiopharmaceutical a radioisotope used in medical procedures
radius of gyration the radius at which all of the mass of a rotating body must be
concentrated to have the same moment of inertia as the original
rarefaction the region of a longitudinal wave in which the particles are
further apart than in their equilibrium position
ray a line drawn perpendicular to a wavefront, representing the path
of that wavefront through an optical system
recombination the neutralisation of free electrons and positive ions in an ionised
gas. The energy produced is emitted as electromagnetic waves in
the radio, infrared, visible and ultraviolet spectra.
red giant the stage in the life of a star shortly after it has left the main
sequence and its atmosphere has expanded and cooled
redshift the wavelength shift observed in the spectrum of a star or galaxy
commonly interpreted as a Doppler shift
re-entry the action of entering the Earth’s atmosphere at high velocity on
return from orbit
reference frame a set of axes against which the motion of a body is measured
reflection the return of a wave from a boundary
reflection, angle of the angle between the reflected ray and the normal to the point
of incidence
refraction the change in direction of a wave as it passes from one medium
into another
refractive index the ratio of the speed of light in a vacuum to its speed in a given
relativity the theory based on the equivalence of observations of an event
from different frames of reference, having different velocities and
relaxation time the process by which the magnetisation of a sample of nuclei
return to their original orientations in NMR
relaxation, spin-lattice the exchange of energy between the nuclei and the surrounding
material, which leads to relaxation
relaxation, spin-spin the exchange of energy between the nuclei leading to relaxation
repulsive force a force between two bodies which causes them to move apart
resistance the ratio of the voltage across an electrical component to the
current flowing through it
resistor an electrical component with a specified resistance
resolving power the resolving power of a telescope is the smallest angular
separation between two point sources at which they can be
identified as double
resonance frequency the driving frequency at which the transfer of energy into a
vibrating system is most efficient
resonant mode a system vibrating at its natural frequency
restoring force the force which acts on an object to return it to its equilibrium
position after it has been disturbed
resultant a vector equal to the sum of two or more component vectors
rheostat a variable resistor
rotational inertia the resistance of an object to changes in its rotational motion
rotor the moving part of a motor or generator
RR Lyra variable variable stars with light curves similar to those of Cepheids, but
which have shorter periods of less than a day. They are found in
globular clusters.
Rydberg constant a constant used to calculate the wavelength of spectral lines from
a hydrogen atom

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