Electricity Equations

See the definition of each Electricity subdivision and the main equations used:

→ Electrostatics

In this field of study, all electrical phenomena occur with electrical charges at rest.

• electrical load

Q = Electric charge (C – coulomb);

n = Number of elementary charges;

e = Elementary charge (e = 1.6 x 10 ^{– 19} C).

• Electric force – Coulomb’s Law

F = Electric force (N – Newton);

Q ₁ and Q ₂ = Electric charges (C);

d = Distance between electrical charges (m);

K = Electrostatic constant in vacuum (k = 9.0 x 10 ⁹ Nm ^{– 2} C ^{– 2} ).

• Electric field

E = Electric field (N/C);

F = Electric force (N);

q = Test electrical charge ©.

E = Electric field (N/C);

K = Electrostatic constant in vacuum (k = 9.0 x 10 ⁹ Nm ^{– 2} C ^{– 2} );

Q = Electric charge generating the electric field (C);

d = Distance between the electric charge and any point (m).

• electrical potential energy

E _P = Electric potential energy (J);

K = Electrostatic constant in vacuum (k = 9.0 x 10 ⁹ Nm ^{– 2} C ^{– 2} );

Q eq = Electric charges (C);

d = Distance between electrical charges.

• Electric potential

V = Electric potential (V – volts);

K = Electrostatic constant in vacuum (k = 9.0 x 10 ⁹ Nm ^{– 2} C ^{– 2} );

Q = Electric charge (C);

d = Distance between the electric charge and any point (m).

→ Electrodynamics

In Electrodynamics, electrical phenomena occur with moving electrical charges. The orderly movement of electric charges is called electric current.

• Electric current

i = Electric current (A = ampere);

Q = Electric charge (C);

Δ t = Time interval considered for the flow of electric charges (s).

• Ohm’s Laws

U = Electric potential difference (V);

R = Electrical resistance (Ω – ohm);

i = Electric current (A).

R = Electrical resistance (Ω – ohm);

ρ = Resistivity (Ω .m);

L = Length of conductive material (m);

A = Cross-sectional area (m ² ).

• Combination of resistors in series

i = Electric current (A);

U = Potential difference (V);

R = Electrical resistance (Ω – ohm).

• Connecting resistors in parallel

i = Electric current (A);

U = Potential difference (V);

R = Electrical resistance (Ω – ohm).

• Joule effect

Q = Amount of heat (cal – Calories);

i = Electric current (A);

R = Electrical resistance (Ω – ohm);

Δ t = Time interval (s).

• Electric power

Pot = Electric power (W – watts);

i = Electric current (A);

U = Potential difference (V);

R = Electrical resistance (Ω – ohm).

• Energy consumed

E = Energy consumed (kWh – kilowatt-hour);

Pot = Power of electrical equipment (kW);

Δ t = Time interval (h).