Introduction to Electrical Engineering

Fundamental Concepts

• Electric charge is a fundamental property of matter that makes it experience force in an electromagnetic field, and is measured in coulombs (C).
• Electric current is the rate of flow of electric charge and is measured in amperes (A).
• Voltage, or electric potential difference, is the electric potential energy difference per unit charge between two points, and is measured in volts (V).
• Resistance opposes the flow of electric current, and it is measured in ohms (Ω).

Circuit Analysis

• Ohm's Law states that the voltage across a resistor is directly proportional to the current flowing through it (V = IR).
• Kirchhoff's Current Law (KCL) states the total current entering a junction equals the total current leaving the junction.
• Kirchhoff's Voltage Law (KVL) states that the sum of voltage drops around any closed circuit loop equals zero.
• Series circuits connect components end-to-end, providing the same current through each component; total resistance equals the sum of individual resistances (R_total = R1 + R2 + ...).
• Parallel circuits connect components so the voltage across each component is the same; the reciprocal of total resistance is the sum of reciprocals of individual resistances (1/R_total = 1/R1 + 1/R2 + ...).
• Power is the rate at which electrical energy is transferred, calculated as P = VI = I^2R = V^2/R, and measured in watts (W).

AC Circuits

• Alternating Current (AC) periodically reverses direction and changes magnitude continuously with time.
• Frequency measures the number of complete AC waveform cycles per second and is measured in hertz (Hz).
• Period is the time for one complete AC waveform cycle and is measured in seconds (T = 1/f).
• Root Mean Square (RMS) Value is the effective value of an AC waveform, equivalent to the DC value that dissipates the same power in a resistive load; for sinusoidal waveforms, V_rms = V_peak / √2.
• Impedance is the total opposition to current flow in an AC circuit, including resistance and reactance (capacitive and inductive), and is measured in ohms (Ω).
• Capacitive Reactance is the opposition to current flow due to a capacitor in an AC circuit; X_C = 1 / (2πfC), where C is capacitance in farads (F).
• Inductive Reactance opposes current flow due to an inductor in an AC circuit; X_L = 2πfL, where L is inductance in henries (H).
• Phase Angle is the difference in phase between voltage and current in an AC circuit and is determined by reactance.
• Power Factor is the ratio of real power to apparent power in an AC circuit, expressed as cos(φ), where φ is the phase angle between voltage and current.

Semiconductor Devices

• Diodes are semiconductor devices that allow current to flow in one direction only.
• Transistors amplify or switch electronic signals and electrical power.
• Bipolar Junction Transistors (BJTs) are current-controlled devices with a base, collector, and emitter.
• Field-Effect Transistors (FETs) are voltage-controlled devices with a gate, drain, and source.
• MOSFET (Metal-Oxide-Semiconductor FET) is a type of FET widely used in integrated circuits.
• Integrated Circuits (ICs) are microchips with interconnected transistors, resistors, and other components that perform specific functions.

Digital Electronics

• Digital Signals are discrete, representing information as binary digits (bits), either 0 or 1.
• Logic Gates are the basic building blocks of digital circuits, performing logical operations like AND, OR, NOT, NAND, NOR, XOR, and XNOR.
• Boolean Algebra is a mathematical system used to analyze and simplify digital circuits.
• Flip-Flops are bistable circuits that store one bit of information.
• Registers are collections of flip-flops storing multiple bits of data.
• Microprocessors are ICs containing a central processing unit (CPU) capable of executing instructions.
• Memory devices store digital data, including RAM (Random Access Memory) and ROM (Read-Only Memory).

Electromagnetism

• Magnetic Field is a vector field describing the magnetic influence of electric currents and magnetic materials.
• Magnetic Flux measures the quantity of magnetism, accounting for the strength and extent of a magnetic field, and is measured in webers (Wb).
• Magnetic Flux Density is the amount of magnetic flux per unit area, measured in teslas (T).
• Faraday's Law of Electromagnetic Induction states that a changing magnetic field induces a voltage (electromotive force) in a conductor.
• Inductance is the property of an electrical conductor where a change in current induces a voltage in the conductor itself (self-inductance) and in nearby conductors (mutual inductance), measured in henries (H).
• Transformers transfer electrical energy from one circuit to another through electromagnetic induction.

Power Systems

• Power Generation is the production of electrical power from sources like fossil fuels, nuclear energy, and renewable sources (solar, wind, hydro).
• Transmission Lines are high-voltage lines transporting electrical power over long distances.
• Distribution Networks are lower-voltage networks distributing electrical power to end-users.
• Substations transform voltage levels and provide switching and protection for power systems.
• Power System Protection includes systems of devices and strategies protecting power system equipment from faults and abnormal conditions.

Control Systems

• Feedback Control systems measure the output and use that measurement to adjust the input to achieve a desired output.
• Open-Loop Control systems do not measure the output to adjust the input.
• Transfer Function is a mathematical representation of the relationship between a system’s input and output.
• Stability is the ability of a control system to maintain a desired output without oscillating or becoming unstable.
• PID Control is a common control algorithm using proportional, integral, and derivative terms to adjust the control output.

Signal Processing

• Analog Signals are continuous signals that vary smoothly over time.
• Digital Signals are discrete signals representing information as binary digits (bits).
• Sampling converts an analog signal into a digital signal by taking discrete samples at regular intervals.
• Quantization assigns a discrete value to each sample in a digital signal.
• Fourier Transform is a mathematical technique decomposing a signal into its constituent frequencies.
• Filters are circuits or algorithms that selectively pass or block certain frequencies in a signal.

Telecommunications

• Modulation is the process of encoding information onto a carrier signal for transmission.
• Amplitude Modulation (AM) varies the amplitude of the carrier signal in proportion to the message signal.
• Frequency Modulation (FM) varies the frequency of the carrier signal in proportion to the message signal.
• Digital Modulation techniques transmit digital data, such as ASK (Amplitude Shift Keying), FSK (Frequency Shift Keying), and PSK (Phase Shift Keying).
• Multiplexing combines multiple signals into a single channel for transmission.
• Communication Channels are the physical media used to transmit signals, including wired cables, optical fibers, and wireless radio waves.

Explore the fundamentals of electrical engineering, covering electric charge, current and voltage. Learn about Ohm's Law and Kirchhoff's Laws in circuit analysis. Discover how these principles underpin power generation and electronics.