Download App

STD 11 - 14. waves and sound — JEE STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceJEESTD 11 - 14. waves and sound4 Marks
MCQ
A string is stretched between fixed points separated by $75.0\, cm$. It is observed to have resonant frequencies of $420\, Hz$ and $315\, Hz$. There are no other resonant frequencies between these two. Then, the lowest resonant frequency for this string is .... $Hz$
  • ✓
    $105$
  • B
    $1.05$
  • C
    $1050$
  • D
    $10.5$
✓

Answer

Correct option: A.
$105$
a
Given $\frac{\mathrm{nv}}{2 \ell}=315$ and $(\mathrm{n}+1) \frac{\mathrm{v}}{2 \ell}=420$

$\Rightarrow \frac{n+1}{n}=\frac{420}{315} \Rightarrow n=3$

Hence $3 \times \frac{\mathrm{v}}{2 \ell}=315 \Rightarrow \frac{\mathrm{v}}{2 \ell}=105 \mathrm{Hz}$

The lowest resonant frequency is when

$\mathrm{n}=1$

Therefore lowest resonant frequency

$=105 \mathrm{Hz}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

JEE STD 11 Science question papers→Gujarat Board STD 11 Science question papers→Gujarat Board question paper generator→

Similar questions

Diffraction effects are easier to notice in the case of sound waves than in the case of light waves because
→
A ball is thrown vertically upward with an initial velocity of $150\,m / s$. The ratio of velocity after $3\,s$ and $5\,s$ is $\frac{x+1}{x}$. The value of $x$ is $...........$ Take $\left(g=10\,m / s ^2\right)$
→
A person is swimming with a speed of $10\, m /s$ s at an angle of $120^{\circ}$ with the flow and reaches to a point directly opposite on the other side of the river. The speed of the flow is $'x'$ $m / s$. The value of $'x'$ to the nearest integer is ..............
→
$n$ Millikan oil drop experiment, a charged drop of mass $1.8 \times {10^{ - 14}}kg $ is stationary between its plates. The distance between its plates is $0.90 cm$ and potential difference is $2.0$ kilo volts. The number of electrons on the drop is
→
The work function of caesium is $2.14\, eV$. Find the wavelength of the incident light if the photo current is brought to zero by a stopping potential of $0.60\, volt$ ............ $nm$
→
Velocity of a particle is in negative direction with constant acceleration in positive direction. Then, match the following columns.
Colum $I$ Colum $II$
$(A)$ Velocity-time graph $(p)$ Slope $\rightarrow$ negative
$(B)$ Acceleration-time graph $(q)$ Slope $\rightarrow$ positive
$(C)$ Displacement-time graph $(r)$ Slope $\rightarrow$ zero
  $(s)$ $\mid$ Slope $\mid \rightarrow$ increasing
  $(t)$ $\mid$ Slope $\mid$ $\rightarrow$ decreasing
  $(u)$ |Slope| $\rightarrow$ constant
→
The threshold wavelength for photoelectric effect of a metal is $6500 Å$. The work function of the metal is approximately .......... $eV$
→
A container of mass $M$ containing liquid of mass $m_0$ is kept on weighing machine. A ball of mass $m$ is released from rest from given position. Then choose correct option just after ball is released
→
The output sinusoidal current versus time curve of a rectifier is shown in the figure. The average value of output current in this case is
→
A plane polarized monochromatic $EM$ wave is travelling a vacuum along $z$ direction such that at $t\, = t_1$ it is found that the electric field is zero at a spatial point $z_1$ . The next zero that occurs in its neighbourhood is at $z_2$. The frequency of the electromagnetic wave is:
→