Fundamental Concepts of Electricity

Fundamental Concepts of Electricity

• Electricity is a fundamental force of nature, arising from the presence and interaction of electric charges.
• Electric charge is a fundamental property of matter, existing as positive and negative charges.
• Like charges repel, and unlike charges attract.
• The SI unit of electric charge is the Coulomb (C).
• Electric current is the flow of electric charge through a conductor.
• The SI unit of electric current is the Ampere (A), defined as one Coulomb per second.
• Electric current can be direct current (DC), flowing in one direction, or alternating current (AC), periodically reversing direction.
• Voltage is the electric potential difference between two points in a circuit, measured in volts (V). It drives the flow of current.
• Electric potential energy is the energy a charged particle possesses due to its position in an electric field.
• Resistance is a measure of a material's opposition to the flow of current, measured in Ohms (Ω).

Ohm's Law

• Ohm's law states the relationship between voltage, current, and resistance in an electrical circuit.
• Mathematically, it is expressed as: V = IR, where V is voltage, I is current, and R is resistance.
• Ohm's law is fundamental in analyzing and designing electrical circuits.
• Ohm's Law only holds true for ohmic materials, where the resistance is constant over a range of voltages and currents.

Electric Circuits

• An electric circuit is a closed path through which electric current can flow.
• Essential components of a circuit include:
  • Voltage source (e.g., battery, generator)
  • Conductors (wires)
  • Load (resistor, light bulb, motor)
  • Control switches (to open/close circuit)
• Series circuits have current flowing through each component in a single path.
• Parallel circuits have components connected to the same two points of the circuit, hence current branches.
• Kirchhoff's laws are vital in analyzing complex circuits. Kirchhoff's current law states that the current entering a node (junction) must equal the current leaving that node. Kirchhoff's voltage law states that the sum of the voltage drops across all elements in any closed loop of a circuit must equal zero.

Types of Resistors

• Resistors are passive electronic components that oppose the flow of current.
• Types include fixed resistors, variable resistors (potentiometers), and thermistors (whose resistance changes with temperature).
• Resistors in series add up their resistances to create a total resistance.
• Resistors in parallel have a reciprocal relationship between the individual and total resistances.

Electrical Power and Energy

• Electrical power is the rate at which electrical energy is transferred in a circuit, measured in watts (W).
• It is calculated using the equation P = IV, where P is power, I is current, and V is voltage.
• Electrical energy is the total amount of work done by an electrical component, measured in joules (J) or kilowatt-hours (kWh).
• Energy is calculated using the equations: Energy = Power × Time or Energy = I²Rt for a resistive load.

Magnetism and Electromagnetism

• Magnetism is a force that acts on moving charges and magnetic materials.
• Electric currents produce magnetic fields.
• Electromagnetic induction is the process of generating a voltage (and current) by changing a magnetic field.
• Faraday's Law of Induction describes how a changing magnetic field creates an electromotive force (voltage).
• Lenz's Law describes the direction of the induced current.
• Electromagnets exploit the effect of electric currents generating magnetic fields.

Capacitance

• Capacitance is the ability of a component to store an electric charge. It is a fundamental property of capacitors.
• Capacitors store energy in an electric field.
• Capacitors are composed of two conducting plates that store the charge.
• The capacitance depends on the geometry of the capacitor and the material between the plates.

Inductance

• Inductance is the property of a component to oppose any change in current flowing through it.
• Inductors are electronic components designed to create an inductance.

AC Circuits

• AC circuits use alternating current, which continuously changes magnitude.
• AC circuits include components like capacitors and inductors, which play a role in determining how the current and voltage respond to the changes.
• Impedance of an AC circuit is an equivalent to resistance in DC circuits, but takes into account the reactive nature of these components.
• AC circuits can involve resonance, where the circuit's impedance is minimal.