Podcast
Questions and Answers
What are the three assumptions used to study a physical system represented by an electric circuit?
What are the three assumptions used to study a physical system represented by an electric circuit?
The three assumptions are:
- Electrical effects happen instantaneously throughout a system (lumped-parameter system).
- The net charge on every component in the system is always zero.
- There is no magnetic coupling between the components in a system.
What are the steps involved in problem solving when dealing with electric circuits?
What are the steps involved in problem solving when dealing with electric circuits?
The steps are:
- Identify what's given and what's to be found
- Sketch a circuit diagram or other model
- Think of several solution method and decide which one to use
- Calculate a solution
- Use your creativity
- Test your solution
An electric circuit is a physical representation of an actual electrical system.
An electric circuit is a physical representation of an actual electrical system.
False
What is the basic unit of length in the International System of Units (SI)?
What is the basic unit of length in the International System of Units (SI)?
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What is the formula for calculating electric potential in SI units?
What is the formula for calculating electric potential in SI units?
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What is the symbol for the prefix 'micro'?
What is the symbol for the prefix 'micro'?
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What is the speed of light in meters per second?
What is the speed of light in meters per second?
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What is the value of the electronic charge in coulombs?
What is the value of the electronic charge in coulombs?
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What is the formula for calculating power in terms of voltage and current?
What is the formula for calculating power in terms of voltage and current?
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What is the sign convention for power when the current is flowing in the same direction as the voltage drop across an element?
What is the sign convention for power when the current is flowing in the same direction as the voltage drop across an element?
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If the power absorbed by an element is negative, it means that the element is actually supplying power.
If the power absorbed by an element is negative, it means that the element is actually supplying power.
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What is the law of conservation of energy?
What is the law of conservation of energy?
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What is the formula for calculating energy in terms of power and time?
What is the formula for calculating energy in terms of power and time?
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Study Notes
Basic Electricity & Electronics
- This course covers fundamental concepts in electricity and electronics.
- It introduces circuit variables, definitions, and calculations.
Circuit Variables
- Electric Circuit: A mathematical model approximating the behavior of an actual electrical system.
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Assumptions:
- Electrical effects happen instantaneously throughout a system (lumped-parameter system)
- Net charge on every component is always zero.
- No magnetic coupling between components.
Course Specifications
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Assessment Methods:
- Final Exam (40%)
- Mid-term Exam (20%)
- Tutorial Quiz (10%)
- Lecture Quiz (10%)
- Semester Work (10%)
List of References
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Essential Books:
- Fundamental Electrical and Electronic Principles by Christopher R. Robertson (3rd edition)
- Basic Engineering Circuit Analysis by J. Irwin and R. Nelms (10th edition)
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Recommended Books:
- Electric Circuits by J.W. Nilsson and Susan A. Riedel (8th edition)
Problem Solving
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Steps:
- Identify given and what needs to be found.
- Sketch a circuit diagram or visual model.
- Think of several solution methods and choose one.
- Calculate a solution.
- Use creativity.
- Test the solution.
Balancing Power
- Electrical Source (a & b): The power source for the home.
- Wires (c, d, e): Carry current from the source to devices.
- Devices (f, g, h): Lamps, televisions, etc. requiring power.
The International System of Units (SI)
- Basic Units: Length (meter, m), Mass (kilogram, kg), Time (second, s), Electric Current (ampere, A), Thermodynamic temperature (kelvin, K), Amount of substance (mole, mol), Luminous Intensity (candela, cd).
Derived Units in SI
- Units derived from the basic ones to describe concepts like force, energy, power, charge, potential, resistance, conductance, capacitance, flux, and inductance.
Standardized Prefixes
- Abbreviations to indicate powers of 10 (e.g., kilo = 10³, mega = 10⁶).
Example #1
- Signal travel in a cable at 80% of light speed.
- Calculates cable length (in inches) for 1 nanosecond (ns).
Voltage and Current
- Charge: Bipolar (positive and negative charges).
- Electric Charge: Exists in discrete quantities (integral multiples of elementary charge).
- Electrical Effects: Result from charge separation (voltage) and charge motion (current).
Voltage
- Energy per unit charge: Created by charge separation, measured in volts (V), equivalent to joules per coulomb (J/C).
Signs of the Terminals
- Positive (+) sign in terminal 1 indicates terminal 1 is positive with respect to terminal 2.
- Voltage can exist between terminals even without current flow.
Example #2
- Explains how voltage definitions exist between two terminals. Positive and negative signs in different placements.
Notes
- Plus-minus (algebraic) signs: Conventions to talk about voltage across terminal pairs (without indicating true polarity).
Current
- Electric Current (i): Rate of charge (q) moving past a reference point in a direction, measured in amperes (A). (charge/time).
- Units: Current (amperes, A), charge (coulombs, C), time (seconds, s).
The Direction of Current Flow
- Positive and Negative Ions: Current direction determined by the moving charge (positive or negative).
Direction is Important
- Current direction is a fundamental aspect defined using arrows.
DC and AC
- Direct Current (DC): Constant with time.
- Alternating Current (AC): Changes direction with sinusoidal variation.
Example #3
- A current is applied to a circuit over a certain time.
- The total charge accumulating at the terminal is calculated.
Positive Value/Negative Value
- Voltage drop/rise: Defined terms for voltage relative to two terminals.
- Charge flow: Positive and negative charge flow direction between 2 terminals defined.
Power and Energy
- Power (p): Time rate of expending or absorbing energy (W).
- Energy (w): Capacity to do work (J).
- Power Formula: p = dw/dt = v*i
Positive Sign Convention
- Defining when the power (p=v*i) is absorbed and or supplied by a circuit element in a circuit. Positive and negative signs relation.
Example #4
- Compute power absorbed for each part in a given circuit for the positive and negative sign conventions.
Solution for Example #4
- Computes power absorbed by different two terminal elements according to convention signs in a given circuit diagram.
Example #5
- Calculates the power absorbed by each component in a given circuit, based on the given voltages and currents.
Summary
- Topics Covered: Voltage, Current, Circuit Elements, Passive Sign Convention, and Power calculations.
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Description
Test your understanding of fundamental concepts in electricity and electronics. This quiz covers circuit variables, definitions, and calculations essential for mastering the subject. Prepare for your assessments effectively with this concise quiz.
