AMERICAN INTERNATIONAL UNIVERSITY–BANGLADESH (AIUB)

INTRODUCTION TO ELECTRICAL CIRCUITS LAB

Spring 2024-25

Section: P

Group: 02

Experiment No. 06: Experiment Title: Transient Analysis of RC Series

and RL series using MULTISIM

Submitted to: MD. MAHMUDUL HASAN

Name ID Contribution Remarks

1. EMAMUL KABIR OVI 22-49664-3 15%
2. AL SHAMS MD.
22-49684-3 15%
ROHAN
3. TOUSIF TARIK 23-53577-3 30%
4. SHAFAYAT JAMIL 23-55457-3 20%
5. SAMIRA ALAM DIA 24-57605-2 20%

Date of Performance: 30.04.2025

Date of Submission: 14.04.2025

Comments/Marks :
 Contribution

Serial ID NAME Contribution Percentage

Procedure,
1. 22-49664-3 1. EMAMUL KABIR OVI Result, 15%
Discussion
Abstract,
2. 22-49684-3 2. AL SHAMS MD. ROHAN 15%
Theory
3. 23-53577-3 3. TOUSIF TARIK Calculation 30%
Data Table,
4. 23-55457-3 4. SHAFAYAT JAMIL 20%
Simulation
Theory,
5. 24-57605-2 5. SAMIRA ALAM DIA 20%
Apparatus

Total: 100%
 on or off. After about five-time constants (5τ), the
Title: Transient Analysis of RC Series voltage or current is nearly at its final value. This
is known as the steady state.
and RL series using PSPICE/MULTISIM. • For an RC circuit, the time constant is:
Abstract: τ = R × C
PSpice/Multism is an electrical circuit where R is the resistance and C is the
simulation software with which circuits can be capacitance.
drawn, checked, and simulated for finding • For an RL circuit, the time constant is:
unknown circuit parameter-values and τ = L / R
graphs. The software where L is the inductance and R is the
has component and device library which can resistance.
Time Period (T):
be used for any types of construction,
The time period is the time taken to complete
simulation,
one full cycle of a waveform or pulse. It tells us
and demonstration of circuits
how long each cycle lasts.
Pulse Width (tp):
The objective of this experiment is -
The pulse width is the duration of the "on" time
• Simulation of circuits by using in a pulse. For an ideal square wave, the pulse
components from the Multisim width is half of the time period
library
• Simulation of circuits by writing script
files and analyzing obtained graphs
and results.

Theory:
Time Constant (τ):
The time constant tells us how quickly voltage or [Figure 1 shows an RC circuit made up of a
current changes in RC (resistor-capacitor) and RL resistor (8kΩ) and a capacitor (8µF) connected in
(resistor-inductor) circuits after a switch is turned series with a pulse voltage source. This setup
on or off. After five time constants (5τ), the helps us observe how voltage changes across the
voltage or current is usually very close to its final capacitor over time when a sudden voltage is
value—this is called the steady-state. applied.
• For an RC circuit, the time constant is Figure 2 shows an RL circuit consisting of a
the resistance multiplied by the resistor (8kΩ) and an inductor (50H) in series
capacitance: with the same pulse voltage source. This circuit is
τ=R×C used to study how the inductor responds to a
• For an RL circuit, the time constant is sudden change in voltage. Both circuits help us
the inductance divided by the understand how capacitors and inductors behave
resistance: in time-dependent circuits.]
τ=L/R Apparatus:
Time Period (T):
The time period is the time it takes to complete
1) PC
one full cycle of a repeating signal, like a pulse or 2) Multisim Simulating tools
a waveform.
Experimental Procedure and Data:
Theory and Methodology:
Time Constant (τ): Simulating Circuits by using Components
The time constant shows how quickly voltage or from the Multisim library
current changes in RC (resistor-capacitor) and RL 1. Open the Multisim software window: Start
(resistor-inductor) circuits after a switch is turned → Program → Multisim
2. Open component window from menu bar: 1) If, t = τ,
Place → Components
3. Select Dc source/ Digital Clock/ Step Vc = E (1 - 𝑒 −1 )
Voltage source from components, a resistor,
a = 6.32V
capacitor (for RC) or an inductor (for RL) and
a ground source. 2) If, t = 2τ,
4. For Step voltage: Place → Components →
Vc = E (1 - 𝑒 −2 )
Sources → Signal_Voltage_Sources →
Step = 8.65V
Voltage.
5. Set the source, resistor, capacitor/inductor 3) If, t = 3τ,
values properly.
6. Connect all the elements by using wire as Vc = E (1 - 𝑒 −3 )
necessary and label them properly.
7. Then go to Analysis and Simulation bar = 9.50V
and change it to Transient: Analysis and
Simulation → Transient. And select the 4) If, t = 4τ,
Initial condition to set to zero.
8. Choose the expected output variables from Vc = E (1 - 𝑒 −4 )
output window: Analysis and simulation →
Output → Add output variable. = 9.83V
9. Insert new expressions if needed: Analysis
and simulation → Output → Add 5) If, t = 5τ,
expression.
Vc = E (1 - 𝑒 −5 )
10. Now run the simulation for the designed
circuit and analyze the output from the = 9.94V
simulation grapher view.
11. Perform the analysis as instructed
For RL series circuit,
Calculation and Result:
E = 10 V
For RC series circuit,
R = 8 KOhms
E = 10 V
L = 50 H
R = 8 KOhms
We know, Steady state value, 𝐼𝑚 = E/R
C = 8 µF
= (10/8×103 )
We know, Time constant τ = RC
= 1250 µA
=8×103 ×8×10−6
Time constant, τ = L/R
= 64× 10−3 sec.
= 50/8×103
Voltage Across Capacitor, Vc = E (1 -
𝑒 −1/τ ) = 6.25 ms.
Current, 𝐼𝐿 (t) =
𝐸
(1 - 𝑒 −1/τ ) Data Table 1: For RC series circuit
𝑅

𝝉 Value Time % Charged 𝐕𝐜

1) If t = τ,
Constant
𝐸 1𝝉 64ms 63.58% 6.32V
𝐼𝐿 (t) = (1 - 𝑒 −1 )
𝑅
2𝝉 128ms 87.02% 8.65V
3𝝉 192ms 95.57% 9.50V
= 790.15 µA
4𝝉 256ms 98.3% 9.83V
2) If t = 2τ, 5𝝉 320ms 100% 9.94V
This table shows how the capacitor in the RC circuit
𝐸
𝐼𝐿 (t) = (1 - 𝑒 −2 ) charges over time, reaching nearly full voltage
𝑅
(10V) after about 5 time constants (320ms), with
= 1080.83 µA each step showing how much voltage has built up.

Data Table 2: For RL series circuit

3) If t = 3τ,
𝝉 Value Time % Storage 𝑰𝑳
𝐸
𝐼𝐿 (t) = (1 - 𝑒 −3 ) Constant
𝑅

1𝝉 6.25 ms. 63.64% 790.15 µA

= 1187.76 µA
2𝝉 12.5 ms. 87.05% 1080.83 µA
4) If t = 4τ,
3𝝉 18.75 ms. 95.66% 1187.76 µA
𝐸
𝐼𝐿 (t) = (1 - 𝑒 −4 )
𝑅 4𝝉 25 ms. 98.83% 1227.105 µA

= 1227.105 µA 5𝝉 31.25 ms. 100% 1241.577 µA

5) If t = 5τ,
This table shows how the current through the inductor (IL) in
𝐸
𝐼𝐿 (t) = (1 - 𝑒 −5 ) the RL circuit increases over time, reaching its maximum value
𝑅
gradually, and becomes almost steady after about 5 time
constants (31.25 ms).
= 1241.577 µA
Simulation :
[Note:These calculations help us understand
how the voltage across the capacitor (Vc)
changes over time when a constant
voltage (E = 10V) is applied to an RC
series circuit. The time constant (τ = RC)
tells us how quickly the capacitor charges,
and using it, we can find Vc at different
times. This shows that the capacitor
slowly charges up to the full voltage, and Figure-3: Transient analysis of RC Circuit
we can clearly see how fast or slow this
[This simulation shows how a capacitor charges over time in a
charging happens over time.] RC(Resisitor- capacitor) circuit when connected to a DC
voltage source. The graph on the right displays the voltage
across the capacitor gradually increasing until it reaches the
maximum supply voltage]
 Reference(s):
[1] Robert L. Boylestad,
“Introductory Circuit Analysis”,
Prentice Hall, 12th Edition, New
York, 2010, ISBN 9780137146666.

[2] R.M. Kerchner and G.F.

Corcoran, “Alternating Current
Circuits”, John Wiley & Sons,
Figure-4: Transient analysis of RL Circuit
Third Ed., New York, 1956.

[This simulation shows how current behaves in an [3] http://ee.lamar.edu/eela

RL(Resisitor-Inductor) circuit when a 10V AC source is bs/elen2107/lab5.pdf [Cited:
appliled. The grapah indicates that the current increases 12.01.2014]
gradually as the inductor resists sudden changes,
demonstrating how inductors delay current flow at the
start] http://ee.lamar.edu/eelabs/elen2107/lab6.pdf
[Cited: 12.01.2014]
Discussion:
1. In this experiment, RC and RL series
circuits were constructed.
2. Value time constant was modified as
required and Vc, IL were measured. The
data obtained was inserted into the table.
3. Relevant calculation was done using
experimental data.
4. The analysis was completed effectively
using τ = R×C and τ = L/R
5. Every mentioned step was completed
properly to make sure the simulation
works properly.

Conclusion:
In this experiment, the value of theoretical and
simulated was closely same which determine that
the experiment was successful. The goal of the
experiment was set from the beginning. The
study was described by calculating the voltage
across the capacitor of RC series circuit and
current across the inductor of RL series circuit.