Page 128 - Physics - XI

Waves
8 Waves

EXPERIMENT - 8
Aim
To study the relation between frequency and length of a given wire under constant tension using sonometer.

Apparatus and Materials Required
A sonometer, a set of six tuning forks of known frequencies, hanger with slotted weights, rubber pad, paper
rider, and metre scale

Description of Apparatus
Wedge
W W
Peg 1 2 P
R Pulley
G
Steel wire

Hanger (H)
Slotted weight
Table

Fig. 8.1: A Sonometer

Sonometer
Sonometer is an apparatus which is used to study the vibrations produced by vibrating strings. It is also

called monochord.
It consists of a hollow and rectangular wooden box with a peg G at one
end and a frictionless pulley P at the other end as shown in Fig. 8.1. A 1 A 2
A metal wire is stretched along the length of a sonometer. One end of Prong Prong

the wire is fi xed to the peg G and other end after passing over a pulley P
carries a hanger H to which slotted weights can be attached. Two bridges
W and W are placed over the board and below the wire. The two bridges
2
1
W and W are provided for the purpose of altering the vibrating length N 1 A N 2
1
2
of the wire. 3
Tuning fork: It is a vibrating body of a given frequency. It is a U-shaped Stem
steel bar provided with a handle attached at the bend and called stem.
The two sides of the U-shaped bar are called prongs (Fig. 8.2). When one Fig. 8.2: Tuning fork

of the prongs of the tuning fork is struck gently against a rubber pad, it
begins to vibrate as shown in Fig. 8.2.

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