Electricity Basics: Charge and Current

Electric Charge and Current

• Electric charge: a fundamental property of matter, measured in coulombs (C)
• Positive charge: proton
• Negative charge: electron
• Conductors: materials that allow free flow of electrons (e.g., copper)
• Insulators: materials that resist electron flow (e.g., rubber)

Electric Current

• Flow of electrons from higher concentration to lower concentration
• Measured in amperes (A)
• Types of current:
  • Alternating current (AC): direction of flow changes periodically
  • Direct current (DC): direction of flow remains constant

Voltage and Resistance

• Voltage (V): potential difference between two points, measured in volts (V)
• Resistance (R): opposition to electron flow, measured in ohms (Ω)
• Ohm's Law: V = I × R (voltage = current × resistance)

Power and Energy

• Power (P): rate of doing work, measured in watts (W)
• Energy (E): capacity to do work, measured in joules (J)
• Power formula: P = V × I
• Energy formula: E = P × t (energy = power × time)

Electric Circuits

• Series circuit: components connected one after another
• Parallel circuit: components connected between same two points
• Series-parallel circuit: combination of series and parallel connections

Essential Electrical Quantities

• Capacitance (C): ability of a component to store electric charge
• Inductance (L): ability of a component to store energy in a magnetic field
• Impedance (Z): total opposition to AC current flow

Electric Charge

• Electric charge is a fundamental property of matter, measured in coulombs (C)
• Positive charge is associated with protons
• Negative charge is associated with electrons

Conductors and Insulators

• Conductors are materials that allow the free flow of electrons (e.g., copper)
• Insulators are materials that resist electron flow (e.g., rubber)

Electric Current

• Electric current is the flow of electrons from higher concentration to lower concentration
• Electric current is measured in amperes (A)
• There are two types of current:
  • Alternating current (AC): direction of flow changes periodically
  • Direct current (DC): direction of flow remains constant

Voltage and Resistance

• Voltage (V) is the potential difference between two points, measured in volts (V)
• Resistance (R) is the opposition to electron flow, measured in ohms (Ω)
• Ohm's Law: V = I × R (voltage = current × resistance)

Power and Energy

• Power (P) is the rate of doing work, measured in watts (W)
• Energy (E) is the capacity to do work, measured in joules (J)
• Power formula: P = V × I
• Energy formula: E = P × t (energy = power × time)

Electric Circuits

• Series circuit: components are connected one after another
• Parallel circuit: components are connected between the same two points
• Series-parallel circuit: a combination of series and parallel connections

Essential Electrical Quantities

• Capacitance (C) is the ability of a component to store electric charge
• Inductance (L) is the ability of a component to store energy in a magnetic field
• Impedance (Z) is the total opposition to AC current flow