Practical Physics for B.Sc. Students General Lab I by Rajesh Verma and P.K. Gangwar, is an essential laboratory manual designed as per the FYUGP NEP 3rd semester Physics major and minor syllabus of Dibrugarh University and other Indian universities. Published by Mahaveer Publications, this book provides clear explanations and step-by-step procedures for performing a wide range of fundamental physics experiments. It covers key areas of practical physics with detailed theoretical backgrounds, observation formats, and result analysis. This book is an ideal guide for undergraduate students to build strong experimental skills and a deeper understanding of physics concepts.

MECHANICS EXPERIMENTS (Page 1-59)

Experiment 1: To determine the height of a building using a Sextant (Pages 1-5)

Objective: To measure the height of a tall building using a sextant and trigonometric principles.

Theory: A sextant is an optical instrument used to measure angles between any two visible objects. The height of a building can be calculated using the angle of elevation and the horizontal distance from the base.

Formula:

Height (h) = d × tan(θ)
where: d = horizontal distance from building
       θ = angle of elevation measured by sextant

Procedure:

1. Set up the sextant at a known distance from the building
2. Measure the angle of elevation to the top of the building
3. Record the horizontal distance from the base
4. Calculate height using trigonometric relations
5. Repeat measurements for accuracy

Precautions:

• Ensure sextant is properly calibrated
• Take multiple readings and calculate average
• Account for the height of the sextant above ground

Experiment 2: To study the Motion of Spring and calculate (a) Spring constant, (b) g and (c) Modulus of rigidity (Pages 6-9)

Objective: To determine the spring constant, acceleration due to gravity, and modulus of rigidity using spring oscillations.

Theory: When a mass is attached to a spring, it undergoes simple harmonic motion. The time period depends on the mass and spring constant.

Formulas:

Spring Constant: k = mg/x (static method)
Time Period: T = 2π√(m/k)
Acceleration due to gravity: g = 4π²x/T²
Modulus of Rigidity: η = 8πLmr⁴/T²R⁴

Procedure:

1. Static Method: Hang different masses and measure extensions
2. Dynamic Method: Record time periods for oscillations
3. Plot graphs of load vs. extension and T² vs. mass
4. Calculate spring constant from slope
5. Determine g and modulus of rigidity

Experiment 3: To determine the Moment of Inertia of a Flywheel (Pages 10-15)

Objective: To find the moment of inertia of a flywheel using the principle of conservation of energy.

Theory: When a mass falls from the flywheel axle, its potential energy converts to kinetic energy of translation and rotation.

Formula:

I = (m × r² × (2gh - v²)) / v²
where: I = moment of inertia
       m = falling mass
       r = radius of axle
       h = height fallen
       v = final velocity

Procedure:

1. Wind string around the flywheel axle
2. Attach known mass to the string
3. Release mass and measure time to fall through known height
4. Calculate final velocity and moment of inertia
5. Repeat with different masses

Experiment 4: To determine g and velocity for a freely falling body using Digital Timing Technique (Pages 16-19)

Objective: To measure acceleration due to gravity using digital timing methods.

Theory: For a freely falling body: s = ut + ½gt² If released from rest (u = 0): s = ½gt²

Equipment:

• Digital timer with photogate sensors
• Steel ball
• Electromagnet release mechanism

Procedure:

1. Set up photogate sensors at known distances
2. Release ball from electromagnet
3. Record time intervals digitally
4. Calculate g using kinematic equations
5. Determine velocity at different points

Experiment 5: To determine Coefficient of Viscosity of water by Capillary Flow Method (Poiseuille's method) (Pages 20-25)

Objective: To find the coefficient of viscosity of water using Poiseuille's law for capillary flow.

Theory: Poiseuille's law relates the flow rate through a capillary to the viscosity of the fluid.

Formula:

η = (πr⁴ΔP) / (8lQ)
where: η = coefficient of viscosity
       r = radius of capillary
       ΔP = pressure difference
       l = length of capillary
       Q = volume flow rate

Procedure:

1. Measure capillary tube dimensions accurately
2. Set up constant head apparatus
3. Measure volume of water flowing in given time
4. Calculate flow rate and viscosity
5. Repeat at different temperatures

Experiments 6-10: Material Properties Testing

Experiment 6: Young's Modulus by Optical Lever Method (Pages 26-31) Experiment 7: Modulus of Rigidity by Maxwell's needle (Pages 33-37) Experiment 8: Elastic Constants by Searle's method (Pages 38-44) Experiment 9: Value of g using Bar Pendulum (Pages 45-52) Experiment 10: Value of g using Kater's Pendulum (Pages 53-59)

WAVE & OPTICS EXPERIMENTS (Page 60-111)

Experiment 1: To determine the frequency of an electric tuning fork by Melde's experiment and verify λf = v law (Pages 60-63)

Objective: To find the frequency of a tuning fork using resonance in strings and verify the wave equation.

Theory: When a string is vibrated by a tuning fork, standing waves are formed. The wavelength depends on the frequency and wave velocity.

Formula:

f = v/λ = (1/2l)√(T/μ)
where: f = frequency
       v = wave velocity
       λ = wavelength
       T = tension in string
       μ = linear mass density

Procedure:

1. Set up string with tuning fork vibrator
2. Vary tension to create standing wave patterns
3. Measure wavelength from node-antinode patterns
4. Calculate frequency using wave equation
5. Verify λf = v relationship

Experiment 2: To determine the refractive index of the Material of a prism using sodium source (Pages 64-67)

Objective: To find the refractive index of a glass prism using minimum deviation method.

Theory: The refractive index is related to the angle of minimum deviation and the apex angle of the prism.

Formula:

n = sin[(A + δₘ)/2] / sin(A/2)
where: n = refractive index
       A = apex angle of prism
       δₘ = minimum deviation angle

Procedure:

1. Mount prism on spectrometer table
2. Illuminate with sodium lamp
3. Rotate prism to find minimum deviation position
4. Measure minimum deviation angle accurately
5. Calculate refractive index

Experiments 3-4: Material Properties of Prisms

Experiment 3: Dispersive power and Cauchy constants (Pages 68-79) Experiment 4: Wavelength determination using Michelson's interferometer (Pages 80-84)

Experiments 5-7: Optical Interference and Diffraction

Experiment 5: Wavelength using Fresnel Biprism (Pages 85-90) Experiment 6: Wavelength using Newton's Rings (Pages 91-97) Experiment 7: Thin film thickness measurement (Pages 98-103)

Experiments 8-10: Advanced Optical Measurements

Experiment 8: Spectral analysis using plane diffraction grating (Pages 104-108) Experiment 9: Wavelength determination of spectral lines (Pages 105-108) Experiment 10: Dispersive and resolving power of diffraction grating (Pages 109-111)

General Laboratory Guidelines

Safety Precautions

1. Handle optical equipment with care
2. Never touch lenses or mirrors with fingers
3. Ensure proper electrical connections
4. Wear safety goggles when necessary
5. Report any equipment damage immediately

Data Recording

1. Record all measurements with proper units
2. Note environmental conditions (temperature, humidity)
3. Calculate uncertainties and errors
4. Plot graphs where required
5. Draw proper conclusions from results

Error Analysis

1. Systematic Errors: Due to instrument calibration
2. Random Errors: Due to measurement limitations
3. Personal Errors: Due to observer limitations
4. Calculate percentage errors and standard deviations
5. Suggest improvements for accuracy