Introduction to Electrical Engineering Lecture 1

Questions and Answers

What characteristic distinguishes an ideal voltage source from a practical voltage source?

It has some internal resistance. (correct)

It maintains a constant voltage. (correct)

It has infinite resistance in series.

It can vary its voltage with load.

Which of the following statements about ideal current sources is true?

They can only provide current up to a certain limit.

They maintain a constant current regardless of the load. (correct)

They supply current based on the resistance of the load.

They provide voltage independent of load.

If an ideal current source supplies 300mA to a load of 1kΩ, what will the load current be if the load is changed to 100Ω?

30mA

100mA

300mA (correct)

What is the defining feature of a dependent source?

Its output varies with another voltage or current in the circuit. Signup and view all the answers

Which statement accurately describes a practical current source?

It is represented by an ideal current source in parallel with resistance. Signup and view all the answers

What characterizes an active network?

It has at least one voltage source or current source. Signup and view all the answers

Which statement is true regarding current flow in passive elements?

Current flows from higher potential to lower potential. Signup and view all the answers

What is the power absorbed by an element when the current is -2A and the voltage is -3V?

-6W Signup and view all the answers

Which of the following best describes a branch in a network?

It consists of a single path with one simple element and nodes at each end. Signup and view all the answers

Which statement is correct about voltage definition across an element?

Both value and polarity must be defined. Signup and view all the answers

How is the direction of positive current flow characterized?

It flows out of the positive terminal. Signup and view all the answers

What distinguishes a node in a network?

It is a point of connection between two or more circuit elements. Signup and view all the answers

When is power considered to be supplied by an element?

When positive current flows out of the positive terminal. Signup and view all the answers

What type of circuit element is defined as one that can supply an average power over an infinite time interval?

Active Element Signup and view all the answers

Which circuit element is independent of the current flowing through it?

Ideal Voltage Source Signup and view all the answers

Which of the following statements about passive elements is true?

They can dissipate energy. Signup and view all the answers

What distinguishes a practical source from an ideal source?

It is less reliable in maintaining voltage. Signup and view all the answers

Which component is classified as a passive element that can store energy?

Inductor Signup and view all the answers

What is the relationship of voltage across a resistor to the current through it?

Voltage is proportional to the current. Signup and view all the answers

Which of the following best describes a dependent voltage source?

It relies entirely on current elsewhere in the circuit. Signup and view all the answers

What term refers to the essential circuit concepts such as node, path, loop, and branch?

Network & Circuits Signup and view all the answers

Study Notes

Circuit Elements

Circuit elements define relationships between current and voltage.
If voltage is proportional to current, the element is a resistor.
Key components include:
- Independent voltage source (current independent)
- Dependent current source (dependent on current elsewhere)
- Inductor (derivative of current)
- Capacitor (integral of current)

Active & Passive Circuit Elements

Active elements supply average power (>0), e.g., ideal sources.
Passive elements cannot provide average power (>0), e.g., resistors, capacitors, inductors.
Resistor dissipates energy; capacitors and inductors store and release energy.

Ideal & Practical Sources

Ideal sources provide constant voltage or current, unaffected by circuit elements.
Ideal voltage sources have zero internal resistance; ideal current sources have infinite internal resistance.
Practical sources model ideal sources with internal resistance in series or parallel.

Independent & Dependent Sources

Independent sources maintain constant voltage or current regardless of circuit conditions.
Dependent sources have values proportional to other circuit parameters.
- Types include:
  - Voltage-controlled voltage source (VCVS)
  - Current-controlled current source (CCCS)

Network & Circuits

Networks connect two or more circuit elements; a network becomes a circuit when it has a closed path.
Active networks contain at least one active source (voltage or current).
Passive networks lack any active sources.

Reference Directions

Voltage requires labeling of terminals (+ and -).
Current flow requires a defined direction, using arrows for clarity.
Current directionality:
- Flows from higher to lower potential in passive elements.
- Flows from lower to higher potential in active elements.
Power relationships:
- Positive current out of positive terminal indicates power supply.
- Positive current into positive terminal indicates power absorption.

Network Terminologies

Node: connection point for two or more circuit elements.
Branch: a single path with one element and nodes at each end.
Path: movement from one node to another without repeating nodes.

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Description

This quiz covers the fundamentals of Electrical Engineering as introduced in Lecture 1. Key topics include circuit elements, sources, and their classifications, alongside active and passive circuits. Numerical examples are also provided to enhance understanding.