Musical Pillars Temples often have some pillars portraying human figures playing musical instru- ments, but seldom do these pillars themselves produce music. At the Nellaiappar temple in Tamil Nadu, gentle taps on a cluster of pillars carved out of a single piece of rock produce the basic notes of Indian classical music, viz. Sa, Re, Ga, Ma, Pa, Dha, Ni, Sa. Vibrations of these pillars depend on elasticity of the stone used, its density and shape.
Musical pillars are categorised into three types: The first is called the Shruti Pillar , as it can produce the basic notes — the “swaras”. The second type is the Gana Thoongal , which generates the basic tunes that make up the “ragas”. The third variety is the Laya Thoongal pillars that produce “taal” (beats) when tapped. The pillars at the Nellaiappar temple are a combination of the Shruti and Laya types.
Archaeologists date the Nelliappar temple to the 7th century and claim it was built by successive rulers of the Pandyan dynasty. The musical pillars of Nelliappar and several other temples in southern India like those at Hampi (picture), Kanyakumari, and Thiruvananthapuram are unique to the country and have no parallel in any other part of the world. Fig. .
Superposition of two harmonic waves, one of frequency Hz (a), and the other of frequency 9Hz (b), giving rise to beats of frequency Hz, as shown in (c). SUMMARY . Mechanical waves can exist in material media and are governed by Newton’s Laws. .
Transverse waves are waves in which the particles of the medium oscillate perpendicular to the direction of wave propagation. . Longitudinal waves are waves in which the particles of the medium oscillate along the direction of wave propagation. .
Progressive wave is a wave that moves from one point of medium to another. . The displacement in a sinusoidal wave propagating in the positive x direction is given by y ( x , t ) = a sin ( kx – ω t + φ ) where a is the amplitude of the wave, k is the angular wave number , ω is the angular frequency , ( kx – ω t + φ ) is the phase , and φ is the phase constant or phase angle . .
Wavelength λ of a progressive wave is the distance between two consecutive points of the same phase at a given time. In a stationary wave, it is twice the distance between two consecutive nodes or antinodes. . Period T of oscillation of a wave is defined as the time any element of the medium takes to move through one complete oscillation.
It is related to the angular frequency ω through the relation T = π . Frequency v of a wave is defined as / T and is related to angular frequency by