electric circuits basics

DC Circuits

Basic Concepts

Charge and Current

Charge is an electrical property of the atomic particles of which matter consists, measured in coulombs (C).

1 coulomb = charge transferred by 1 ampere in 1 second or  1 C = 1 A * 1 s = 6.242×10^18 protons

Electric current is the time rate of change of charge, measured in amperes (A).

1 amp = 1 coulomb / sec

A direct current (dc) is a current that remains constant with time. An alternating current (ac) is a current that varies sinusoidally with time.

Voltage

Voltage (or potential difference) is the energy required to move a unit charge through an element, measured in volts (V).

Power is the rate of doing work, the amount of energy transferred per unit time. Measured in watts

Energy is the capacity to do work, measured in joules (J).