JEE PHYSICS MCQ: WAVES

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Two sitar strings "A" and "B" playing the note "Dha" are slightly out of tune and produce beats of frequency

5 \mathrm{~Hz}

. The tension of the string "

\mathrm{B}

" slightly increased and the beat frequency is found to decrease to

3 \mathrm{~Hz}

. What is the original frequency of "

\mathrm{B}

" in hertz, if the frequency of "

\mathrm{A}

" is

427 \mathrm{~Hz}

View answer and explanation

Correct option: B

422

Option B (422) is correct because the original frequency of string B can be either 432 Hz or 422 Hz, but the condition that increasing the tension decreases the beat frequency implies that the original frequency was lower than that of string A.

More Questions from WAVES

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The source of sound generating a frequency of

3\,\,kHz

reaches an observer with a speed of

0.5

times, the velocity of sound in air. The frequency heard by the observer is A source of sound emits waves with frequency

f\mathrm{ }Hz

and speed

V\mathrm{ }m/sec

. Two observers move away from this source in opposite directions each with a speed

0.2\,\,V

relative to the source. The ratio of frequencies heard by the two observers will be Assertion: The wave function of a pulse is given by

y = \frac{3}{{{{\left( {2x + 3t} \right)}^2} + 4}},

it propagates in

(– \mathrm{ve}) \,x

-direction.
Reason: The given wave function is of the form

y = f(kx +\omega t),

which represent a wave travelling in negative

X

-direction. In the fundamental mode, time taken by the wave to reach the closed end of the air filled pipe is

0.01\,\,s

. the fundamental frequency is A rope

5 \mathrm{~m}

long has a total mass of

245 \mathrm{~g}

. It is stretched with a constant tension of

1 \mathrm{~kg}

wt. If it is fixed at one end and shaken by hand at the other end, what frequency of shaking will make it break up into three vibrating segments? Take

g=980 \mathrm{~cm} \mathrm{~s}^{-2}

. If

T

is the reverberation time of an auditorium of volume

V

then