PHYSICS LAB MANUALS

Melde's Apparatus

The following quantities are directly measured in this experiment.

Table II: The details of the physical quantities to be measured.
S. No	Physical quantity	Independent / Dependent	Measured with	Measuring instrument’s
S. No	Physical quantity	Independent / Dependent	Measured with	Minimum	Maximum	Least count
2	Length	dependent	Meter scale
3	Mass	independent	Weighting machine

Take one meter of string and pass over the pulley. Attach a pan of known weight to one end and tie the other end to the tuning fork.
Arrange the tuning fork along the length of the string. This creates transverse vibrations in the string.
Also measure the weight of a known length of the string used in the experiment. Note down these values to calculate the mass/unit length.
Now, close the circuit and adjust the screw till the fork vibrates steadily.

DO NOT TIGHTEN THE SCREW. WHEN IT IS JUST TOUCHING THE METAL STRIP, A SPARK WILL BE OBSERVED, STOP HERE.

DO NOT USE VOLTAGE MORE THAN 6V.
Move the tuning fork (keeping the tension constant)until a single loop is formed with well-defined nodes.
Take care that the vibrations of the string are in the horizontal plane.
Note down the length of the string from the pulley to the tuning fork.
Repeat steps 4-7 to obtain different no of loops by moving the tuning fork away from the pulley.
Repeat the above mentioned steps by arranging the tuning fork perpendicular to length of the string. This creates longitudinal vibrations in the string

How to measure Mass per unit length of string:

Weight of the pan (m) =

Length of the string used in the experiment =

Mass of the string =

Table III: Table for transverse and longitudinal arrangment.

S. No	Load applied in the pan ($M$ gm)	Tension $T = (M+m)g$dynes	No. of Loops “X”	Length of ‘X’ loops (d cm)	Length of each loop $l = \frac{d}{x}$ (cm)	Frequency (Hz)
1.
2.