Sonometer - Transverse laws of strings verification

 

    In the TANSCHE syllabus for first year B.Sc. Physics, one key experiment involves testing the transverse laws of vibrating strings with a sonometer. This experiment is essential for grasping wave mechanics and understanding how transverse waves behave in stretched strings, which is important for many areas in physics and engineering.

    During this hands-on activity, students will explore the principles that dictate string vibrations, such as the connections between frequency, tension, length, and mass per unit length. Using the sonometer, students can directly see how these factors work together, allowing them to confirm the theoretical laws of string vibration through practical experience.

    This post will walk you through the setup, procedure, and important steps needed to accurately test the transverse laws of strings.

Sonometer - Transverse laws of strings verification

Aim:

To verify the transverse laws of strings using a sonometer.

Apparatus required:

Sonometer, tuning forks, weight hanger with weights, knife edges, metre scale, paper rider etc

Formula:

Here,
    T is the tension N
    m is the linear density of the string kg/m
    n is the frequency of the tuning fork Hz
    l is the length of the vibrating segment m

Procedure:

To verify the first law:

A proper tension T is set on the Sonometer wire. A small piece of paper is placed on the wire. A tuning fork with a known frequency is struck, and its handle is pressed against the sonometer wooden box. The length of the wire is adjusted with the help of two knife edges until the paper rider, positioned at the center of the vibrating segment, is thrown off.

Tabular Column 1: To verify nl = constant

Tension T = Mg = ____ N

S.No	Frequency of the tuning fork Hz	Vibrating length m	n x l

To verify the second law:
Select a specific tuning fork with frequency n. The wire is stretched using a 2 kg weight. The length of the wire that vibrates in sync with the tuning fork is measured. This process is repeated with different weights while using the same tuning fork, and the results are recorded in a table.

Tabular Column 2: To verify = constant

                                        Frequency of the tuning fork n = ____ Hz

S.No	Tension N	Vibrating length m

To verify the third law:

For a specific tension (let's say 3 kg), the length of the wire (l) that vibrates in sync with the chosen tuning fork is measured. The experiment is conducted again using three wires made from different materials, maintaining the same tension and tuning fork.

Tabular Column 3: To verify = constant

Tension T =  ____ N Frequency of tuning fork n = ____ Hz

S.No	Linear density of the wire kg/m	Vibrating length m

Result: 

The transverse laws of vibrations of strings are verified.