S.6 Physics Waves Caltec S.6

1 SENIOR SIX PHYSICS PAPER TWO (WAVES ), CONTINUATION ….. (all the streams should copy) BY MR.ALIA AMBROSE MUSICAL NOTES AND SOUND SOUND Sound is any mechanical vibration whose frequency lies within the audible range . sound wave s do not pass through the vacuum. It requires a material medium for their transmission . Experiment to show that sound waves requires a material medium for transmission . (leave about 6 lines for the diagram) When all the air has been removed (pumped out) thus crea ting a vacuum in the bell jar, no sound is heard although the harmer is seen hitting the gong. This shows that sound requires a material medium for their transmission. Compression and rarefaction When sound waves pass through air, variation in pressure occurs . somewhere it is below the normal and at some other point it is above the normal. The condition of air when the pressure is above the normal is called compression and the condition when the pressure is below the normal is called rarefac tion. Qn. Sound propagation in air is considered to be an adiabatic process. Explain. Compression of air causes a rise in temperature unless heat is withdrawn. Rarefaction causes a decrease in temperature unless heat is added. Because air is a poor conduct or of heat, no much heat enters a region of rarefaction nor leaves a region of compression hence sound propagation is an adiabatic process. No heat leaves or enter the system. Characteristics of sound waves . They undergo reflection , refraction, diffraction and interference. Diffraction .is the spreading of sound waves when they pass through openings or around obstacles. Diffraction of sound waves depends on; (i) The size of the aperture; The smaller the aperture the greater the diffraction. (ii) The wavelength; Diffraction increases with wav …