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Linear Circuit Analysis:
  • Charge and Current
  • Work, Power, Voltage, and
          Resistance
  • Kirchoff's Laws
  • Y Delta, Node, and Loop
  • Circuits with Operational
         Amplifiers
  • Network Theorems
  • Analysis of Diode Circuits
  • Capacitance and Inductance
  • First-Order Transient Circuits
  • AC Steady State Analysis
  • Steady State Power
  • The Power Factor
    Introduction

    adv.92g
    circuits.92g
    delta2yt.92g

    • Linear Circuit Analysis:
    Basic Concepts -
    Charge and Current

    ------------

    For this program, the first thing we want to do is to create a new folder on the TI-92. This is accomplished by typing "NewFold circuits" on the Entry Line. By doing this we will be able to save all of the different variable types in this folder.

    The first items to cover are the ideas of Charge and Current. These two properties are related to each other in time by the equations:
         

    Where Q is the charge, El is the number of electrons, ec is the charge of a single electron = 1.6019 * 10-19, T is time, and I is the current.


    To help remember this formula, lets start a formula sheet by way of the Text Editor.

    To start a new Text session,

    • Press [APPS]  [9]  [3].
    • Press [ENTER].
    After naming the Text File, press [ENTER] twice.
    Then enter the formulas to be remembered on the first and second lines. After the formulas are entered,
    • Press [F2] (Command)
    • Press [1]
    To make the formulas transferable to the Home screen. We will be coming back to the text editor every time we are introduced to a new formula.

    Now lets split the screen so that we have the Text Editor on top and the home screen on the bottom.
    • Press Mode.
    • Press [F2] (Page 2).
    • From Split Screen select TOP-BOTTOM and press [ENTER].
    • From Split Screen Ratio select 1:2 and press [ENTER] twice.

    Now with the screen split, and the curser on the first equation of the Text Editor
    • Press [F4] (Execute), to move the equation to the Entry Line.
    • Press [2nd] [APPS] to select the Home Screen.
    Determine the Charge on 7.753 * 1037 electrons.
    DeCarlo. page 31 prob 1a

    To solve this problem, enter the values of ec (The charge of an electron.) and El (The number of electrons.) on the Entry Line. Then call the equation from the Text Editor.

    • Press 1.6019 [2nd] [EE] -19ec and [ENTER].
    • Press 7.573 EE 37 el and [ENTER].
    • Press [2nd] [APPS].
    • Scroll up to the first equation.
    • Press [F4]. (Execute)
    The value for ec (The charge of an electron) is a constant. Therefore it never changes and should be locked.
    • Press[2nd] VAR-LINK.
    • Press [F4] to select ec.
    • Press [F1] then [6] to lock the variable.
    • Press [2nd] QUIT to return to the main screen.
    If 7.573 * 1037 electrons moves uniformly from one end of the wire to the other in 1ms (millisecond), what current flows through the wire?
    DeCarlo. page 31 prob 1b

    To solve this problem, enter the values of Q (The charge from the last problem.) and t (The number of seconds.) on the Entry Line. Then call the equation from the Text Editor.

    • Press 1.213 [2nd] [EE] -19q and [ENTER].
    • Press 1 EE -3 t and [ENTER].
    • Press [2nd] [APPS].
    • Scroll to the second equation.
    • Press [F4]. (Execute)
    How many electrons must pass a given point in 1 minute to produce a current of 10 A?
    DeCarlo. page 31 prob 1c

    Since this problem is not related to any of the previous problems we need to delete the variables. This problem requires that we use both of the previously stored formulas. After combining both of the formulas and solving for El (The number of electrons) we are given the new equation to solve for.


    This formula is also added to the Text file.
    • Type Delvar q,t,i,el on the Entry Line and press [ENTER].
    • Press [F2] (Algebra) then [1] (solve)
    • Enter the Second equation and solve for Q (The charge).
    • Substitute this result into the First equation and solve for El (The total number of electrons). Notice that the value for ec (The charge of an electron) is displayed in its inverted form in the answer.
    • Input the known variables into their respective places. In this case
      enter 10 [i] [2nd] : 60 [t]
      (60 seconds = 1 minuet)
    For the graph of the charge, Show the graph of the current.
    DeCarlo. page 31 prob 1e

    To solve this problem we need to use the differential relationship between current and charge.



    This formula is also added to the Text file.

    This is drawn using a piecewise function on the TI-92

    Since the function for the charge is defined in the y(x) Editor, Finding the graph for the current is a simple matter of graphing the derivative. The derivative of y1(x) is defined and stored in y2(x).

    In an effort to make piecewise functions easier to define, I have written a program entitled pcewise that is available in circuits.92g.


    • Press [Diamond] Y= to open the y(x) editor.
    • Scroll to y2 and press [ENTER].
    • Press [2nd]  d  [(]  y1 [(]  x [)]  [,] x  [)]  [ENTER].
    • Press [Diamond] GRAPH to graph the function.

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