Sound Flashcards
define wavelength
the distance travelled by a wave in one time period of vibration of the particle of the medium s
speed of sound depends on
- density (inverse)
- temperature (direct)
- humidity (direct)
speed of sound not affected by
change in pressure
how are electromagnetic waves formed
electromagnetic waves are formed by the periodic vibrations of the mutually perpendicular electric and magnetic fields in a plane normal to the direction of wave propagation
transfer energy as photons
define reflection of a sound wave
the return of a sound wave on striking a surface such as wall, metal sheet, etc. back in the same medium
requirement of reflection of sound wave
size of reflecting surface must be bigger than wavelength of sound wave
define echo
the sound heard after reflection from a distant obstacle after the original sound has ceased
condition for echo
- minimum distance between source and reflector in air must be 17 m
- size of reflector must be large enough as compared to wavelength of the sound wave
- intensity of sound should be such that the reflected sound reaching the ear is sufficiently loud to be audible
define reverberation
if there are repeated reflections at the reflected surface, the sound gets prolonged
use of echo
sound ranging
echo depth sounding using ultrasonic waves
properties of ultrasonic sound
- travel undeviated through a long distance
- can be confined to a narrow beam
- not easily absorbed in a medium
define natural vibrations
periodic vibrations of a body in the absence of any external force on it
the period of vibration depends on shape or size of the body
why do natural vibrations only occur in vaccum
the presence of a medium around the sound wave offers some resistance to it, and hence the amplitude does not remain constant
how is frequency related to length of air column
inversely related
how is frequency related to radius of string
inverse
how is tension related to frequency
direct