few general formulas

[nix85]

notice energy content of a wave is proportional to the amplitude squared

twice the voltage, 4 times the energy

human hearing is logarithmic

[lancaIV]

work = force * distance moved unit

horizontal /vertical : it is difficult to say to ' a (human) worker' :

you moved (horizontal) only ,by Physics definition You  did not ' work'-ed !

Paying the ' mover/worker' time or not !?


Sincere
OCWL
post scriptum : beside active(P = ) ,reactive(Q = )  and apparent power (S = )a fourth : complex power




                                             F = ILxB force on a conductor in a magnetic field - laplace




Lorentz Force and Laplace "Force"  relativity,by strict condition attention(here without arrows) :     


                                                   F(L) = q x v x B                      F(L)= BLI 

https://www.mpoweruk.com/machines.htm




Michael Faraday showed that passing a current through a conductor freely suspended in a fixed magnetic field creates a force which causes the conductor to move through the field.
Conversely, if the conductor rather than the magnet is constrained then the magnet creating the field will move relative to the conductor.
More generally, the force created by the current, now known as the Lorentz force, acts between the current conductor and the magnetic field, or the magnet creating the field.



The magnitude of the force acting on the conductor is given by:


F = BLI

Where F is the force on the conductor, L is the length of the conductor and I is the current flowing through the conductor

[nix85]

here is the same with small corrections + some useful facts

wavelength = c/f
f = 1/T
momentum = mv
Kinetic Energy ke = 1/2 mv²
centrifugal/centripetal force: F = mv²/r
point body angular momentum momentum unit: L = r x p kg m/s
Force = Mass * acceleration
Work = force * distance moved  unit: newton meter or joule or Work = Mass * Gravity * Height
Work = Change in Energy
Power = work / time = force * displacement / time = force * velocity
Power (hp,watt) = work(ENERGY)/time aka time rate of energy transfer
Energy = Power x Time
A = V/T
for capacitor circuit V=C*(dv/dt)*R
XL= 2πfL
XC= -1/2πfC
Z = sqrt(R² + (Xc - Xl)²)
F = 1/6.28(LC)
F = 1/2π√LC
F = 1/2πL/R for inductor
C= L*(2πFr)²
Fc = 1/2πRC cutoff frequency of an RC low pass filter
ohms law: V = IR
power per second:
P = IV
P = I²R copper losses
P = V²/R
P=VI*PF apparent power (V and I are average, RMS)
energy stored in an inductor E = LI²/2
energy stored in an cap E = 1/2 QV and E = CV²/2
for capacitor and inductor circuit V=IZ
I = C dv/dt current through a cap
1 Volt = 1 Joule/Coulomb
1 Watt = 1 Joule/Second
1 Ampere = 1 Coulomb/Second
V × A = J/C × C/s = J/s = Watt
electric energy E = IVt and E = (V²/R)t
1F = 1C / 1V - amount of electric charge in coulombs that is stored per 1 volt
C = Q / V and C = kA/d
E = F / Q electric field (N/C or V/m) is force per charge
F = qE + qv x B lorentz law, em forces on a charge
R = 80*pi^2*(L/W)^2 rad. res. of antenna where L=length of antenna, and W = wavelength
t = L/R inductor time constant, after ~5t (transient time) current reaches 99.5%
t = RC for RC circuit, after 5RC cap is 99.5% charged
transformer size is proportional to B MAX =V/F
in alternator emf leads flux by 90°+
energy content of wave is proportional to the amplitude squared P = E²
Z = sqrt( L / C ) cable impedance
Ohm = volt / amp
reactive load temporary stores energy, not waste it (unless PS cant take it back)
v = L(di/dt) BACKEMF from an inductor
Short circuit current = V / alternator internal resistance
V=-N*dΦ/dt voltage - farraday's law
V = BLv induced voltage - farraday law for moving conductor
flux density = amper x turns x core permeability x core area / m² (T)
F = ILxB force on a conductor in a magnetic field - laplace
as load increases, current in the conductor must increase to balance the forces: I = F/BL


phase velocity is speed of particular frequency in particular medium

Destructive interference occurs when two identical waves are superimposed exactly out of phase. A standing wave is one in which two waves are superimposed but their phase varies from 0 - 180 to produce a wave that varies in amplitude but does not propagate. Nodes are points of no motion in standing waves.

impedence of an atenna is repeated every half wavelength down from the antenna, it does not matter what the characteristic impedance of the transmission line is (have to take into account velocity factor of the feedline)

characteristic impedance of uniform transmission line is the ratio of the voltage and current of a single wave propagating along the line; that is, a wave travelling in one direction in the absence of reflections in the other direction.

The first evidence that a capacitor and inductor could produce electrical oscillations was discovered in 1826 by French scientist Felix Savary. He found that when a Leyden jar was discharged through a wire wound around an iron needle, sometimes the needle was left magnetized in one direction and sometimes in the opposite direction. He correctly deduced that this was caused by a damped oscillating discharge current in the wire, which reversed the magnetization of the needle back and forth until it was too small to have an effect, leaving the needle magnetized in a random direction. American physicist Joseph Henry repeated Savary's experiment in 1842 and came to the same conclusion, apparently independently.

The 50-ohm compromise
For air dielectric coax, the arithmetic mean between 30 ohms (best power handling) and 77 ohms (lowest loss) is 53.5 ohms, the geometric mean is 48 ohms. Thus the choice of 50 ohms cam be considered a compromise between power handling capability and signal loss per unit length, for air dielectric.

But wait, there is perhaps a more practical reason for choosing fifty ohms:  a coaxial cable with polyethelene (PE) dielectric (ER=2.25) has minimum loss at 51.2 ohms, with (D/d=3.6). Thanks to Per!

displacement current is current through a cap. it has the same units as electric current density, and it is a source of the magnetic field just as actual current is. However it is not an electric current of moving charges, but a time-varying electric field.

power factor = true power / aparent power
Apparent power is RMS voltage x RMS current
Reactive power = sqrt(apparent²-real²)

ELECTRIC POTENTIAL ENERGY dependent on the charge experiencing the electric field
ELECTRIC POTENTIAL only dependent on the position of the object

if cap is charged to 1000v, each plate is charged to +/- 500v

envelope (peak) detector, 1/fc << RC << 1/fm, fc freq. of a carrier, fm freq. of the message

diodes are nonlinear, resistance changes with current through them (at higher currents internal ohmic resistance becomes prevalent over pn potential barrier)

linear circuit is one in which the electronic components' values (such as resistance, capacitance, inductance, gain, etc.) do not change with the level of voltage or current in the circuit. Linear circuits are important because they can amplify and process electronic signals without distortion. An example of an electronic device that uses linear circuits is a sound system.

common emitter amplifier, voltage gain, no current gain, signal is phase shifted 180°
common collector amplifier aka "emitter follower" current gain, no voltage gain
common-base amplifier voltage gain, no current gain

[nix85]

but you don't have to fight gravity to do work,
accelerating the mass horizontally from rest is also work

"work is a measure of energy transfer when force is applied in a certain direction"

[lancaIV]

but you don't have to fight gravity to do work,
accelerating the mass horizontally from rest is also work

"work is a measure of energy transfer when force is applied in a certain direction"

https://en.wikipedia.org/wiki/Work_(physics)


this can be discussed,up to the point " positive" or "negative" work ,physical valuation !


A force is said to do positive work if (when applied) it has a component in the direction of the displacement of the point of application.


A force does negative work if it has a component opposite to the direction of the displacement at the point of application of the force.




http://physics.bu.edu/~duffy/py105/Energy.html
Work and energy
positive work - negative work - no work


If you pick a book off the floor and put it on a table, for example, you're doing positive work on the book, because you supplied an upward force and the book went up.


If you pick the book up and place it gently back on the floor again, though, you're doing negative work, because the book is going down but you're exerting an upward force, acting against gravity.


If you move the book at constant speed horizontally,you don't do any work on it, despite the fact that you have to exert an upward force to counter-act gravity.