Lab Report #4

John Noel

10/07/2020

Capacitance

Introduction:

Capacitors are the building blocks of the every circuit they can store charge and perform various functions in circuits and electronics. Here the charge on the plates of capacitor is directly proportional to voltage across the capacitor. Now the relation will be after the multiplying the capacitance on the capacitor will be,

Q=CV

Figure 1 RC Circuit Picture Source: analog.com

Here C is a proportional constant of capacitance and its unit is Farad (1F=1columb/volt).Now more on this the voltages of the capacitor will be depends upon initial voltages across the capacitor, time constant and product of RC, Here time constant (t) is rate of decreasing time of RC value of capacitor, Now the relationship of V (t) is:,

The relation shows that when capacitor is fully charged then the voltages across the plates reaches at the final value of the voltages you initially applied. Now you see the phenomenon of discharging of the capacitor, at the same time the product RC describes the rate of charging as well as the rate of discharging.

Objectives:

 Familiarization with breadboard circuitry of RC series circuit

 Determine the exponential decay of time constant and effect of RC values

Apparatus:

i. PC with Simulink Software

ii. Breadboard

iii. Connecting wires

iv. D.C. Power supply

v. 10k ohm Resistor

vi. 100µF capacitors

Procedure

Step 1 (On Software)

Figure 2 RC circuit on Simulink Picture source: Simulink

1. First of all power on the PC and open the software of Simulink on it

2. Now starts the software with new file.

3. The circuit is complete with components of RC circuits that is shown in figure

4. Run the circuit and check the charging and discharging phenomenon of capacitor.

5. Use the Scope to measure the graphical values and after this take the Screenshot of all the graphs and circuits from the software.

Step 2 (On Hardware)

Figure 3 RC circuit on Breadboard Picture Source: analog.com

1. Take the all components of the circuit on table

2. Connect the circuit as shown in figure

3. Now put the DC supply with 3.3volts to circuit

4. Connect the DMM to circuit for take the values of current.

5. Calculate the time-constant value of the circuit

6. Now tabulate and graph of the all of results

Safety and Precautions:

· Make the simple connections on the breadboard as you can possible.

· Make the tight connection of connecting wires on breadboard.

· Don't make any loose connection on the breadboard which causes of the short circuit.

· On Simulink software the keep less seconds of run time of circuit for better graphical results.

Data Collection & Results:

Set the output of PC Simulink with configuration of 3.3v and time for 30 second to the circuit. Now you can see the graph of increasing the voltages over the time at charging of capacitor from 0 to maximum. While on discharging of capacitor the curve value is decreasing over time from maximum to 0.

Figure 4 Charging of Capacitor Picture source: Simulink

Figure 5 Discharging of Capacitor Picture Source; Simulink

Questions & Answers:

Q1: What is the total equivalent capacitance?

Answer .The total equivalent capacitance in parallel or series is calculated by including the sum of each capacitor's capacitance.

Q2: How could a capacitor is energy stored in it?

Answer: The energy stored by a capacitor of a given capacitance, the Terminal voltages across the terminals of which is also known, is directly proportional to both the capacitance and the square of the potential difference.

Q3: Why did half of the capacitor charging energy go in parasitic resistance irrespective of resistance value?

Answer: We know half of that energy is dissipated in heat in the resistance of the charging path, and there is only QV (b)/2 are finally stored on the capacitor at equilibrium.

Conclusion & Comments:

In this lab lesion first of all we familiar with RC series circuit on theoretical basis and the some relationships of charge Q and Voltages V(t) of the capacitor. After this we make a series circuit on Simulink software and take the values of the charging and discharging of the capacitor. After this place the circuit on breadboard and connects with 3.3v supply to it. The voltages of hardware circuit are measured by voltmeter and after finding the values we recorded the error of 0.1v of hardware values.

In this lab the main conclusion is about capacitor is that the current is passing through the capacitor is directly proportional to the capacitance of capacitor. The difference between software and hardware values which is called error and we can say it as due to random error.