Basic Electrical Quantities

1. Definition

Basic electrical quantities are the fundamental physical properties used to describe and analyze electrical systems.
They form the building blocks for understanding how electricity behaves in circuits.

2. Main Quantities

2.1 Electric Charge (Q)

Definition: A fundamental property of matter responsible for electric phenomena.
Unit: Coulomb (C)
Symbol: Q or q
Formula: Q = I . t where I is current (A), t is time (s).

Electrical charge

2.2 Electric Current (I)

Definition: The rate of flow of electric charge.
Unit: Ampere (A)
Symbol: I
Formula: I = Q/t where Q is charge (C), t is time (s).

Electric Current A simple electric circuit, where current is represented by the letter i.

2.3 Voltage (V)

Definition: The work done per unit charge to move a charge between two points.
Unit: Volt (V)
Symbol: V or U
Formula: V = W/Q where W is work or energy (J), Q is charge (C).

Voltage

Batteries are sources of voltage in many electric circuits.

2.4 Resistance (R)

Definition: Opposition to the flow of electric current in a conductor.
Unit: Ohm (Ω)
Symbol: R
Formula: R = V/I where V is voltage (V), I is current (A).

Resistence

A 75 Ω resistor, as identified by its electronic color code (violet, green, black, gold, red). Used to apply resistence in an electric circuit.

2.5 Power (P)

Definition: The rate at which electrical energy is converted to another form (heat, light, motion).
Unit: Watt (W)
Symbol: P
Formula:
- P = V.I

Power