Alexander Fufaev
My name is Alexander FufaeV and here I write about:

Physical Quantities and Their Units

Table of contents
  1. Force
  2. Angular momentum
  3. Torque
  4. Energy
  5. Power
  6. Pressure
  7. Charge
  8. Voltage
  9. Resistance
  10. Electric field
  11. Magnetic field
  12. Capacitance
  13. Inductance
  14. Thermal capacity (heat capacity)

Angular momentum

Orbital angular momentum and velocity of a mass during a circular motion

Symbol: \(L\)
Unit of angular momentum: \(\mathrm{Js}\) (Joule second)
Example: \( L ~=~ 10^{-34} \, \mathrm{Js} \) is the magnitude of the orbital angular momentum of an electron in the atom.


Symbol: \(W\)
Unit of energy: \(\mathrm{J}\) (Joule)
Example: \( W ~=~ 30 \, 000 \, 000 \, \mathrm{J} \) is the energy released when one kilogram of coal is burned.


Symbol: \(P\)
Unit of power: \(\mathrm{W}\) (Watt)
Example: \( P ~=~ 2000 \, \mathrm{W} \) is the power of a kettle.


Symbol: \(\mathit{\Pi}\)
Unit of pressure: \(\mathrm{Pa}\) (Pascal)
Example: \( \mathit{\Pi} ~=~ 100 \, 000 \, \mathrm{Pa} \) is the air pressure of the earth's atmosphere.

Mechanical Pressure (Force per Area) on a Plate
Pressure is force per area.


Symbol: \(Q\)
Unit of charge: \(\mathrm{C}\) (Coulomb)
Example: \(Q ~=~ 1.6 \cdot 10^{-19} \, \mathrm{C} \) is the charge of an electron.

Electric positive / negative charge - attraction and repulsion Hover the image!
Positive and negative charges.


Symbol: \(U\)
Unit of voltage: \(\mathrm{V}\) (Volt)
Example: \(U ~=~ 100 \, 000 \, 000 \, \mathrm{V} \) is the voltage between a thundercloud and the earth.

Relationship between voltage and kinetic energy Hover the image!
Voltage is energy per charge.


Symbol: \(R\)
Unit of resistance: \(\mathrm{\Omega}\) (Ohm)
Example: \(R ~=~ 100 \, \mathrm{\Omega} \) is the resistance of an ohmic conductor to which 200 volts are applied and through which 2 amps flow.

Simple circuit with one resistor
Electrical resistance in a simple circuit.

Electric field

Symbol: \(E\)
Unit of electric field: \( \frac{ \mathrm{V} }{ \mathrm{m} } \) (Volt per meter)
Example: \(E ~=~ 1000 \, 000 \, \frac{ \mathrm{V} }{ \mathrm{m} } \) is the electric field between the bottom and top of a thundercloud.

Two positive charges - electric field lines
Electric field of two positive charges.

Magnetic field

Symbol: \(\class{violet}{B}\)
Unit of magnetic field: \( \mathrm{T} \) (Tesla)
Example: \(\class{violet}{B} ~=~ 20 \, \mathrm{T} \) creates a superconducting coil in a nuclear fusion reactor.

Magnetic Field Lines of a Current-Carrying Coil
Magnetic field of a current-carrying coil.


Symbol: \(C\)
Unit of capacitance: \( \mathrm{F} \) (Farad)
Example: \(C ~=~ 100 \, \mathrm{\mu}\mathrm{F} \) is the capacitance of a given capacitor.

AC voltage applied to a capacitor
A capacitor with a certain capacitance in an alternating current circuit.


Symbol: \(L\)
Unit of inductance: \( \mathrm{H} \) (Henry)
Example: \(L ~=~ 500 \, \mathrm{mH} \) is the inductance of a given coil with current flowing through it.

Inductive reactance of the coil in AC circuit
Coil with a certain inductance in an AC circuit.

Thermal capacity (heat capacity)

Symbol: \(C\)
Unit of thermal capacity: \( \frac{\mathrm{J}}{\mathrm{K}} \) (Joule per Kelvin)
Example: \(C ~=~ 4190 \, \frac{\mathrm{J}}{\mathrm{K}} \) is the heat capacity of one liter of water.

Temperature change of water by supply of thermal energy
Water has a certain heat capacity