INEL 3105 Electrical Systems Analysis Electrical and Computer Engineering Department University of Puerto Rico at Mayagüez

 This course is the foundation on which most other courses in the electrical (or computer) engineering curriculum rest. For this reason, put in as much effort as you can. Study regularly (on a daily basis)!!! Problem solving is an essential part of the learning process. Solve as many problems as you can! Base of knowledgeTake notes and Read (everyday!)Analysis I problem solvingSolve problems ask questions

 An electric circuit is an interconnection of electrical devices, and each component of the circuit is known as an element.  Electric circuits are used in numerous electrical systems to accomplish different tasks.  For the purpose of circuit studies, we use simplified representations (or models) of the real devices.  Our goal in this course will be to study the behavior of the circuits: How do they respond to a given input? How do the interconnected elements and devices in the circuits Interact? Simple Flashlight Circuit

Physical Device Solution Process: 1.Define Variables 2. Write equations 3.Solve equations Linear Circuit ModelModel

 The concept of electric charge is the underlying principle for explaining all electrical phenomena.  Charge is an electric property of the atomic particles of which matter consists.  An electric charge q has two attributes: amount and polarity.  The amount of charge is expressed in coulombs (C) in the International System of Units. Nucleus (protons and Neutrons) electrons

 The polarity of the charge is either positive or negative.  For instance, the charge carried by an electron is  q e = x10-19 C  A proton bears the same amount of charge but with positive polarity. SmartArt turns your bullet points into graphics in a single click. You can even change your graphic layout to find just the right way to express your idea. Nucleus (protons and Neutrons) electrons

 The voltage vab between two points a and b in an electric circuit is the energy needed to move a positive charge of 1C from a to b; mathematically,  Voltage (or potential difference) is the energy required to move a unit charge through an element, measured in volts (V), where 1V = 1J/C.

The plus (+) and minus (-) signs are used to define reference direction or voltage polarity.  The v ab can be interpreted in two ways: (1) point a is at a potential of v ab volts higher than point b, or (2) the potential at point a with respect to point b is v ab. Two equivalent representations of the same voltage vab

 Power is the time rate of expending or absorbing energy, measured in watts (W).  The electric power consumed or supplied by a circuit element at any instant of time equals the product of the voltage across the element and the current through it:  p = vi  If the power has a + sign, power is being delivered to or is being absorbed by the element.  If, on the other hand, the power has a – sign, power is being supplied by the element.  But how do we know when the power has a positive or a negative sign?

 Current direction and voltage polarity play a major role in determining the sign of power.  Passive sign convention is satisfied when the current enters through the positive terminal of an element and p = +vi. If the current enters through the negative  terminal, p = -vi.  Unless otherwise stated, we will follow the passive sign convention.

 The principle of conservation of energy must be obeyed in any electrical network.  This means that the power supplied in a network is exactly equal to the power absorbed.  Stated differently, the algebraic sum of power in a circuit, at any instant of time, must be zero:  Σp = 0 With custom layouts you design your own slide arrangements. You can create new kinds of documents with PowerPoint. Easily create everything from business pitchbooks to family photo albums.

 Energy is the capacity to do work, measured in joules (J).  The energy absorbed or supplied by an element in some time interval of duration T seconds is obtained as follows:  The electric power utility companies generally measure energy in terms of the kilowatt-hour (kWh), where 1 kWh = 3.6x106 J

E1.1 Determine the amount of power absorbed or supplied by the elements in the following figure.

E1.2 Determine the unknown variables in the following figure.

E1.3 Find the power that is absorbed or supplied by the elements in the following figure.