1.

Audible frequencies have a range of 20 Hz to 20 xx 10^(3) Hz. Express 't' is range in tems of (i) period T, (ii) wavelength air at, (iii) angular frequency w. (Given velocity of sound in 0^(@)C =331 m//s).

Answer»

Solution :Velocity of sound in air at `0^(@)` C = 331 m/s.
Audible frequencies, `lambda_(1) = 20 Hz`,
`lambda_(2)= 20 xx 10^(3)` Hz
(i) Period (T):
Time period `T= 1/gamma`, we get,
`THEREFORE T_(1) =1/gamma_(1) =1/20 = 0.05` s
`T_(2) = 1/gamma_(2) = 1/(20 xx 10^(3)) = 0.055 xx 10^(-3)`s
`therefore` Time period RANGE is `0.055 xx 10^(-3)` s. ,
(ii) Wavelength `lambda`:
From the formula, `lambda = v/gamma`
`therefore lambda_(1) =v/gamma_(1) = 331/20 = 16.55`m
and `lambda_(2) =v/gamma_(2)= 331/(20 xx 10^(3)) = 0.0165`m
`therefore` Wavelength ranges is 16.55 m to 0.0165 m.
(III) Angular frequency `omega`:
From the formula, `omega = 2pi gamma`
`therefore omega = 2 PI gamma_(1)= 2pi xx 20 = 40 pi "rads"^(-1)`
and `omega_(2) = 2pi gamma_(2) = 2pi xx 20 xx 10^(3)`
`=40 pi xx 10^(3)` rad/s.
`therefore` Angular frequency range is `40 pi` to `40 pi xx 10^(3)` rad/s.


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