# Unit 7: Alternating current

## About Course

Course Title: Exploring Alternating Current

Course Description:

Unit 7: Alternating Current explores the fundamental principles and characteristics of alternating current (AC) circuits. Through theoretical instruction, laboratory experiments, and practical demonstrations, students will explore concepts such as AC waveforms, voltage and current relationships, impedance, and power in AC circuits. The unit will cover different types of AC circuits, their behavior, and the applications of alternating current in physics, engineering, and everyday life.

Course Outline:

1. Introduction to Alternating Current

– Overview of alternating current: current that reverses direction periodically

– AC waveforms: sinusoidal, square, triangular, and sawtooth waveforms

– Frequency and period: measures of the rate at which AC cycles repeat

– Importance of AC circuits in electrical power distribution, electronics, and signal processing

2. AC Voltage and Current Relationships

– Representation of AC voltage and current using phasors and complex numbers

– Instantaneous, peak, peak-to-peak, rms (root mean square), and average values of AC voltage and current

– Phasor diagrams: graphical representations of AC voltage and current relationships

– Analysis of AC circuits using phasor techniques and complex impedance

3. Resistance, Inductance, and Capacitance in AC Circuits

– Impedance: combination of resistance, inductance, and capacitance affecting the flow of AC current

– Resistive circuits: impedance equal to resistance, phase angle of zero degrees

– Inductive circuits: impedance equal to inductance, phase angle of +90 degrees

– Capacitive circuits: impedance equal to capacitance, phase angle of -90 degrees

4. Series AC Circuits Analysis

– Analysis of series AC circuits containing resistance, inductance, and capacitance

– Calculation of total impedance, current, voltage, and phase angle in series AC circuits

– Phase relationships between voltage and current in series AC circuits

– Applications of series AC circuits in power factor correction, impedance matching, and resonance

5. Parallel AC Circuits Analysis

– Analysis of parallel AC circuits containing resistance, inductance, and capacitance

– Calculation of total admittance, current, voltage, and phase angle in parallel AC circuits

– Impedance matching and power factor correction in parallel AC circuits

– Applications of parallel AC circuits in filter design, impedance matching, and power distribution

6. Resonance in AC Circuits

– Resonance: phenomenon where the impedance of a circuit is minimized at a specific frequency

– Series resonance: condition where capacitive and inductive reactances cancel each other out

– Parallel resonance: condition where circuit impedance is minimized due to resonance

– Applications of resonance in tuning circuits, filters, and impedance matching networks

7. Power in AC Circuits

– Real power, reactive power, and apparent power in AC circuits

– Power factor: measure of the phase difference between voltage and current in an AC circuit

– Calculation of power factor, power factor correction, and power factor improvement techniques

– Efficiency and power loss in AC circuits, including resistive, inductive, and capacitive loads

8. Three-Phase AC Systems

– Three-phase AC generation and transmission: advantages in power generation and distribution

– Balanced and unbalanced three-phase AC systems: analysis of currents and voltages in balanced and unbalanced loads

– Three-phase AC motors: types, operation, and applications in industrial and commercial systems

– Three-phase power measurement and power factor correction in three-phase AC systems

Course Delivery:

The course will be delivered through a combination of lectures, laboratory experiments, demonstrations, and multimedia presentations. Real-world examples and practical applications will be integrated into the curriculum to illustrate the relevance of alternating current concepts. Computer simulations and visualization tools may also be used to enhance learning and comprehension.

Assessment:

Student learning will be assessed through quizzes, laboratory reports, homework assignments, midterm exams, and a final examination. Evaluation criteria will include understanding of alternating current concepts, proficiency in solving problems, and ability to apply principles to analyze real-world phenomena. Regular feedback and opportunities for hands-on experience will be provided to support student learning and mastery of the material.

Prerequisites:

Students enrolling in this course should have a basic understanding of electric circuits, including DC circuits and Ohm’s law. Familiarity with algebra, calculus, and basic concepts of physics, such as forces and energy, is recommended but not required. A strong willingness to engage in problem-solving and critical thinking is essential for success in this course.

By the end of Unit 7, students will have developed a solid understanding of alternating current and its behavior in electrical circuits. They will be proficient in analyzing AC circuits, interpreting AC waveforms, and applying AC principles to solve problems related to power distribution, electronics, and signal processing.