University Of Education Lahore,

Faisalabad Campus
Lab Report
Submitted By:
Furqan Asghar
Submitted To:
Dr. Gulam Mustafa
Subject:
Applied Physics
Semester:
1st semester
Roll Number:
bsf23005066
Programme:
BS Computer Science
Shift & Section:
Morning (A)
Department:
Information Sciences

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Practical 1:
Resonance in an RLC Series Circuit:
Objective:

To experimentally determine the resonance frequency in a series RLC circuit and compare this to the
expected resonance value.

Introduction:

The voltage through an RLC series circuit will be measured as a function of frequency for a fixed applied
voltage. The frequency for which the rms voltage attains a maximum value is the resonance frequency.
The expected resonance frequency is given by equation 1.
1
=
𝐹
2𝜋√𝐿𝐶

Principle:

Resonance in a series RLC circuit occurs when the reactive effects of the inductor and capacitor cancel
each other out, resulting in a purely resistive circuit.

Equipment's:

• Series RLC circuit components (resistor, inductor, capacitor)

• Breadboard and connecting wires
• Function generator
• Ampere meter (current measuring device)
• Multimeter

Procedure:

• Assemble the series RLC circuit on the breadboard, connecting the resistor, inductor, and
capacitor in series.
• Use the multimeter to measure and record the values of the resistor (R), inductor (L), and
capacitor (C).
• Connect the function generator to the circuit to provide an AC signal.
• Connect the ampere meter in series with the circuit to measure the current flowing through it.
• Set the function generator to produce a sinusoidal waveform at a low frequency.
• Gradually increase the frequency, noting the frequency at which the current through the circuit
is maximized.
• Identify the frequency at which the current through the circuit is at its maximum. This is the
resonance frequency.

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 • Record the current amplitude at the resonance frequency using the ampere meter.
• Calculate the expected resonance frequency using the formula:
1
=
𝐹
2𝜋√𝐿𝐶

• where L is the inductance and C is the capacitance.

• Compare the experimentally determined resonance frequency with the expected resonance
frequency (theoretical).
• Percentage Difference
𝑓(𝑒𝑥𝑒𝑟𝑖𝑚𝑒𝑛𝑡) − 𝑓(𝑡ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙)
%= ⋅ 100
𝑓(𝑡ℎ𝑒𝑜𝑟𝑒𝑡𝑖𝑐𝑎𝑙)

Circuit Diagram:

Observations:

Current (I)mA Frequency (f)

0.1 100
0.6 550
1 100
1.7 1500
2.3 2800
1.6 5600
1 9500
0.6 16600
0.1 34000

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Resonance Frequency:

F (experimental)=2800Hz

F (theoretical)= 3000Hz Percentage Error:

%𝐸𝑟𝑟𝑜𝑟
=1.25%

Practical 2:
Resonance in an RLC Parallel circuit:
Certainly! To create a practical RCL (resistor, capacitor, and inductor) parallel circuit, you'll
need the following components:

Equipment's:
 Resistor (R)
 Capacitor (C)
 Inductor (L)
 Power supply
 Breadboard and jumper wires
 Multimeter

Procedure:
 Place the resistor, capacitor, and inductor on the breadboard.
 Connect one end of each component to a common node (ground rail).
 Connect the other end of the resistor, capacitor, and inductor to separate nodes on the
breadboard.

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  Connect the free ends of these components to a common node (positive rail).
 Connect the positive terminal of the power supply to the common positive node on the
breadboard.
 Connect the negative terminal of the power supply to the common ground node.
 Use the multimeter to measure the resistance of the resistor (R), the capacitance of the
capacitor (C), and the inductance of the inductor (L).
 Turn on the power supply and apply the desired voltage.
 Measure the voltage drop across each component using the multimeter.
 Observe how the circuit responds to the applied voltage.

Circuit Diagram:

Remember to use appropriate resistor, capacitor, and inductor values based on your circuit
requirements. Also, be cautious with voltage levels and make sure not to exceed the
component ratings.
This practical setup allows you to observe the characteristics of an RCL parallel circuit and
study the interactions between the resistor, capacitor, and inductor when connected in
parallel.

Observations:
Frequency(Hz) Current(mA)
1k 3.2
2k 2.6
3k 1.9
4k 1.4
5k 1.5
6k 2
7k 2.5
8k 2.8
9k 3.1
10k 3.2

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Graph:

Practical 3:
Conversion of Galvanometer into Ammeter
Galvanometer:
A galvanometer is very sensitive instrument to detect the current. It can be easily converted
into ammeter and voltmeter.

Aim:
To convert the given galvanometer of known resistance and of the known figure of merit into an
ammeter of the desired range and to verify the same.

Materials Required:
 Galvanometer
 Shunt resistor
 Connecting wires
 Power supply
 Resistors for calibration (optional)

Theory:

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For the conversion of the galvanometer into the ammeter, shunt resistance is required.
Following is the formula:

Where I is the range of conversion

Circuit Diagram:

Procedure:
 The total number of divisions on either side of the galvanometer scale should be equal and denoted
by n.
 Current Ig must be calculated for the full-scale deflection using Ig = nk.
 The shunt resistance value is calculated using the formula

The shunt resistance S has a small value such that the range is not available in the resistance
box. To obtain the value of this small resistance, wires of copper, manganin, etc are used with
suitable diameter and length.

 Let the length of the wire be 2 cm more than the calculated value of I such that there is 1 cm extra
available at each end. Mark points on each end of the wire and connects it to the two terminals of the
galvanometer. The wire should be such that the points are on the outside of the terminal screws. A
galvanometer with the shunt wire will now work as an ammeter with the range I.
 The electrical connections must be the same as in the circuit diagram.
 To observe maximum and minimum deflection in the galvanometer, insert the key and adjust the
rheostat.
 Note the readings from the galvanometer scale and the corresponding ammeter reading.
 Record the observations.

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Calculations:
The resistance of the galvanometer, G =

The figure of merit, k =

Number of divisions in the galvanometer scale, n =

Current for full-scale deflection, Ig = nk

Range of conversion, I =

Verification:
Least count of the galvanometer converted into an ammeter = I/n =

Table for the verification for converted ammeter

Serial no. Galvanometer reading Ammeter reading I2 Difference I2 – I1

Deflection Ө Current in Amp

I1 = Ө x L.C

1.

2.

3.

Result:
The conversion is perfect as the difference between the actual and measured value of currents is
very small.

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Precautions:
 Calculate the resistance accurately
 Same range conversion ammeter should be used for the verification
 The length of the shunt wire must be correct

Practical 4:
Conversion of Galvanometer into Voltmeter
Aim:
To convert the given galvanometer (of known resistance and figure of merit) into a voltmeter of
desired range and to verify the same.

Apparatus Required:
 Galvanometer
 Series resistor
 Connecting wires
 Power supply
 Resistors for calibration (optional)

Theory:
A galvanometer is an ideal device that is capable of detecting even the weakest electric currents
in an electric circuit. It features a coil suspended or pivoted between concave pole faces of a
strong laminated horseshoe magnet. The galvanometer shows the deflection when an electric
current is passed through the coil. The deflection is directly proportional to the current passed.
A voltmeter is an instrument used for estimating the electrical potential difference between 2
points in an electric circuit.

Series resistance required for conversion:

V-range of conversion

Diagram:

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Procedure:
1. Connect the resistance box in series combination with the galvanometer and take the plugs of
resistance R.
2. A and B are the fixed terminals and C is the variable terminal of the rheostat.
3. Now the galvanometer functions as a voltmeter of range V Volts.
4. Take out the plugs of calculated resistance R from the resistance box.
5. By using a key, adjust the movable contact of the rheostat such that the deflection of the
galvanometer becomes maximum.
6. Note both the readings of the galvanometer and voltmeter.
7. Convert the readings of the galvanometer into volts.
8. Find the difference in the reading. This difference between voltmeter reading and galvanometer
reading gives the error.
9. By moving the variable contact of rheostat, take 5 readings covering the range of voltmeters from 0-3
Volts.

Record your observation:

The Least count of galvanometer converted into voltmeter = V/n =

sl.no Reading of galvanometer into voltmeter Standard voltmeter Standard voltmeter reading
reading V2 V2 – V1

deflection The potential difference in

volts V1

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 2

Calculation:
The resistance of the given galvanometer G =

The figure of merit k =

Number of divisions in galvanometer scale n =

Current for full scale deflection = Ig = nk =

Range of conversion =

Resistance to be placed in series with galvanometer R=V/Ig-G =

Precautions:
 Calculate the resistance accurately
 Use the same range conversion voltmeter should be used for verification
 Use correct length shunt wire.

Result:
The value of the actual and measured value of the potential difference is very small and
conversion is perfect.

Practical 5:
Determination of High Resistance using a Neon Flash Lamp
Aim:
To determine the resistance of a high-value resistor using a neon flash lamp and a known
capacitor.

Materials:

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  Neon flash lamp
 High-value resistor (R)
 Known capacitor (C)
 Power supply
 Connecting wires
 Multimeter (optional)

Procedure:
1. Connect the neon flash lamp in series with the high-value resistor (R) and the known
capacitor (C). Ensure proper electrical connections.
2. Connect the circuit to a power supply. Make sure the voltage is within the operating
range of the neon flash lamp.
3. Charge the capacitor by closing the circuit for a specific duration (e.g., 10 seconds). This
will allow the capacitor to store electrical energy.
4. Open the circuit and discharge the capacitor through the neon flash lamp. The flash
lamp will emit a brief flash of light.
5. Measure the time it takes for the neon flash lamp to completely discharge. This can be
done using a stopwatch or a timer.
6. Record the time taken (t) for the neon flash lamp to discharge completely.
7. Calculate the time constant (τ) of the circuit using the formula τ = R * C, where R is the
resistance of the high-value resistor and C is the capacitance of the known capacitor.
Calculation:
8. τ = R * C
9. Calculate the resistance (R) of the high-value resistor using the formula R = τ / C.
Calculation:
10. R = τ / C
11. Record the calculated resistance value.
12. Optionally, you can verify the resistance value using a multimeter by connecting it in
series with the high-value resistor and measuring the current flowing through the
circuit. Then, use Ohm's Law (R = V / I) to calculate the resistance, where V is the
voltage across the resistor and I is the current flowing through it.

Table of Readings:
Reading Time taken (t) Time constant (τ) Resistance (R)
(seconds) (seconds) (ohms)
1 10.5 0.0015 1500
2 9.8 0.0014 1400
3 11.2 0.0016 1600
4 10.1 0.00145 1450

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 5 10.7 0.00155 1550
Explanation:
In this practical, we use a neon flash lamp and a known capacitor to determine the resistance
of a high-value resistor. The capacitor is charged and then discharged through the neon flash
lamp, which emits a flash of light. By measuring the time it takes for the flash lamp to
discharge completely, we can calculate the time constant (τ) of the circuit.
The time constant (τ) is calculated using the formula τ = R * C, where R is the resistance of the
high-value resistor and C is the capacitance of the known capacitor. From the time constant,
we can then calculate the resistance (R) using the formula R = τ / C.
By recording multiple readings of the time taken for the flash lamp to discharge and
performing the necessary calculations, we can determine the resistance of the high-value
resistor. The table above shows five readings with their corresponding time taken, time
constant, and resistance values.

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