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Turbo Pascal Chain module
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1985-07-29
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15KB
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219 lines
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? (**************************************************)
? (* *)
? (* Elementary Electricity *)
? (* *)
? (* Tutorial No. 4 *)
? (* *)
? (* Series-Parallel Resistors *)
? (* *)
? (* Version 1.0 *)
? (* *)
? (* This program illustrates how resistances *)
? (* may be connected to include both series *)
? (* and parallel branches in the same circuit. *)
? (* The student is expected to calculate the *)
? (* equivalent resistance of a number of such *)
? (* circuits. *)
? (* *)
? (* Written by T. J. Meyers July 18,l985 *)
? (* *)
? (**************************************************)
INTRODUCTION
; The circuits in this program include both series and
;parallel branches. To arrive at correct numerical solutions
;to the problems that follow you must first have mastered
<problems of the type set forth in the preceding tutorials.
;You can return to the menu and make a new program selection
#by typing MENU when the A> appears.
SCHEMATIC DIAGRAM I
A Series-Parallel Circuit
= R-1
= a b
= ........./\ /\ /\...............
= : \/ \/ :
= - : R-2 :
= _:_ :
= 1.5 V _____ ..../\ /\ /\.... :
= | : \/ \/ : :
= + : / : : :
= :.../ ......: :..:
= d: R-3 :c
= sw-1 : :
= :.../\ /\ /\...:
= \/ \/
=
=Study this diagram carefully. Make a good working copy on
=a piece of paper. You will need it.
SCHEMATIC DIAGRAM II
A Series-Parallel Circuit
= R-1
= a b c
= ......./\ /\ /\......................
= - : \/ \/ : :
= _:_ / /
= 1.5 V _____ \ R-2 \ R-3
= : / /
= + : \ \
= : / : :
= :..../ ....................:..........:
= sw-1 d
=
=Study this diagram carefully. Make a good working copy on
=a piece of paper. You will need it.
ANALYSIS OF DIAGRAMS
=Carefully compare, point by point, the two diagrams which you
=have just drawn. Though they may appear to be different they
really are the same circuit.
=The charges leave the negative terminal of the dry cell, flow
?to point a, pass through resistor R-1 to point b, then continue
=to point c. At point c, the charges are faced with a choice.
=They may flow either through resistor R-2 or through resistor
>R-3. Just as a large group of people in a room with two exits
=would do, they use both paths. Part of the charge will flow
<through R-2, part through R-3. The charges then rejoin at
>point d, flow through switch sw-1 (when closed), and return to
=the positive terminal of the cell. How the charges apportion
=themselves between R-2 and R-3 will be left for discussion in
another tutorial.
QUESTIONS:
5 1. What is the total resistance of this circuit?
2. How do we calculate it?
3CALCULATING RESISTANCE IN A SERIES-PARALLEL CIRCUIT
@ Assume the figure below to consist of a single resistor
@ connected in series with two resistors which are themselves
connected in parallel.
@ R-2
@ R-1 :-[******]-:
@ --------[******]---: :--------->
@ :-[******]-:
@ R-3
@ In determining the total resistance in a circuit such as this
@ the RULE is: solve the PARALLEL branch FIRST, then add the
@ result to the resistance (R-1) which is in series.
PROBLEM:
9 Let R-1 = 10 ohms, R-2 = 10 ohms, and R-3 = 10 ohms.
9 Calculate the total resistance. That is, calculate the
9 single resistance which would be equivalent to these 3
resistances combined.
SOLUTION:
! 1. Solve the parallel branch:
' R(p) = (R-2 * R-3) / (R-2 + R-3)
# = (10 * 10) / (10 + 10)
$ = 100/20 = 5 ohms
2. Add the result to R-1:
, R(total) = R-1 + (result from step 1)
, = 10 + 5 = 15 ohms (answer)
8So to repeat our RULE: solve the PARALLEL branch FIRST,
9then add the result to the resistance which is in series.
=The following module will give you practice in solving simple
=circuits of this type. If you experience difficulty, you may
/wish to review the tutorial Parallel Resistors.
PROBLEMS
<You have seen one simple problem solved. Mastery, however,
>comes only with practice. The following problems are provided
=to test your skill and understanding. At a minimum, you will
need paper and pencil.
>Determine each answer using significant figures, and round off
#using standard rounding procedures.
@Remember the RULE: first solve the parallel branch(es) then add
< the result(s) to the series resistor(s).
PROBLEM No. 1
Series Resistors : R-1 =
25 ohms
Parallel Resistors : R-2 =
40 ohms
R-3 =
40 ohms
*The equivalent resistance in ohms is:
&Excellent. Now let's try problem No.2
Sorry. Please try again.
*The equivalent resistance in ohms is:
Good. Now go to problem No. 2
'Wrong again. Let's try that once more.
*The equivalent resistance in ohms is:
#OK this time. Now try problem No.2
Too bad. Wrong again.
*The correct answer is
PROBLEM No. 2
Series Resistors : R-4 =
13 ohms
Parallel Resistors : R-5 =
30 ohms
R-6 =
20 ohms
*The equivalent resistance in ohms is:
'Excellent. Now let's try problem No.3.
Sorry. Please try again.
*The equivalent resistance in ohms is:
Good. Now go to problem No. 3.
'Wrong again. Let's try that once more.
*The equivalent resistance in ohms is:
%OK this time. Now try problem No. 3.
Too bad. Wrong again.
*The correct answer is
PROBLEM No. 3
Series Resistors : R-7 =
Parallel Resistors : R-8 =
R-9 =
*The equivalent resistance in ohms is:
(Excellent. Now let's try problem No. 4.
Sorry. Please try again.
*The equivalent resistance in ohms is:
Good. Now go to problem No. 4.
'Wrong again. Let's try that once more.
*The equivalent resistance in ohms is:
%OK this time. Now try problem No. 4.
Too bad. Wrong again.
*The correct answer is
PROBLEM No. 4
Series Resistors : R-10 =
17.85
Parallel Resistors : R-11 =
23.65
R-12 =
49.75
*The equivalent resistance in ohms is:
(Excellent. Now let's try problem No. 5.
Sorry. Please try again.
*The equivalent resistance in ohms is:
Good. Now go to problem No. 5.
'Wrong again. Let's try that once more.
*The equivalent resistance in ohms is:
%OK this time. Now try problem No. 5.
Too bad. Wrong again.
The correct answer is
PROBLEM No. 5
Series Resistors : R-13 =
Parallel Resistors : R-14 =
R-15 =
2.2 meg
*The equivalent resistance in ohms is:
#Excellent. You have done them all!
Sorry. Please try again.
*The equivalent resistance in ohms is:
&Good. You have completed the program.
'Wrong again. Let's try that once more.
*The equivalent resistance in ohms is:
OK. All done.
Too bad. Wrong again.
The correct answer is
CONCLUSION
Now, let us sum up:
>1. In an electric circuit the current flows from the negative
4 terminal to the positive terminal of the source.
@2. When the circuit branches, as when two or more resistors are
< connected in parallel, the current divides, part flowing
< through each branch. When the branches rejoin so do the
@ individual currents. The total amount of current leaving the
8 branches being exactly equal to the amount entering.
<3. When determining the equivalent (total) resistance of a
; series-parallel circuit, one FIRST determines the total
> resistance of the PARALLEL branch(es). The result is then
$ added to the series resistor(s).
3 Press spacebar to try again
3 To return to the menu
3 first, type (q,Q) to quit
3 then, type (menu,MENU) at A>
5 Press (q,Q) to quit