Download App

14. waves and sound — Physics STD 11 Science — Question

Rajasthan BoardEnglish MediumSTD 11 SciencePhysics14. waves and sound1 Mark
MCQ
A string $2.0\, m$ long and fixed at its end is driven by a $240\, Hz$ vibrator. The string vibrates in its third harmonic mode. The speed of the wave and its fundamental frequency is
  • A
    $320\, m/s, 120\, Hz$
  • B
    $180\, m/s, 80\, Hz$
  • C
    $180\, m/s, 120\, Hz$
  • ✓
    $320\, m/s, 80\, Hz$
✓

Answer

Correct option: D.
$320\, m/s, 80\, Hz$
d
We have:

$f=\frac{n v}{2 \ell}$

$240=\frac{3 \times v}{2 \times 2}$

$\Rightarrow \quad v=320 \mathrm{m} / \mathrm{s}$

Fundamental frequency $=\frac{v}{2 \ell}=80 \mathrm{Hz}$

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

More "M.C.Q (1 Marks)" from 14. waves and sound→14. waves and sound — all question types→Physics STD 11 Science question papers→Rajasthan Board STD 11 Science question papers→Rajasthan Board question paper generator→

Similar questions

The value of Cp - Cv is 1.00R for a gas sample in state A and 1.08R in state B. Let pA and pB denote the pressures and TA and TB denote the temperatures of the states A and B, respectively. It is most likely that:
  1. pA < pB and TA > TB
  2. pA > pB and TA < TB
  3. pA = pB and TA < TB
  4. pA > pB and TA = TB
→
The moment of inertia of a thin uniform rod of mass $M$ and length $L$ about an axis passing through its midpoint and perpendicular to its length is $I_0$. Its moment of inertia about an axis  passing through one of its ends and perpendicular to its length is 
→
A balloon of mass $m$ is descending down with an acceleration $\frac{g}{2}$.  How much mass should be removed from it so that it starts moving up with same acceleration?
→
In an isobaric expansion of an ideal gas, which of the following is zero?
→
A wire can be broken by applying a load of $20\,\,kg$  weight. The force required to break the wire of twice the diameter is ......... $kg\,wt$
→
The specific heat at constant pressure of a real gas obeying $\mathrm{PV}^2=\mathrm{RT}$ equation is :
→
‘Gulab Jamuns’ (assumed to be spherical) are to be heated in an oven. They are available in two sizes, one twice bigger (in radius) than the other. Pizzas (assumed to be discs) are also to be heated in oven. They are also in two sizes, one twice big (in radius) than the other. All four are put together to be heated to oven temperature. Choose the correct option from the following:
→
The relationship between force and position is shown in the figure given (in one dimensional case). The work done by the force in displacing a body from $x = 1 cm$ to $x = 5 cm$  is .......... $ergs$
→
The r.m.s. velocity of a gas is:
→
A planet is revolving around the sun as shown in elliptical path  the orbital velocity of the planet will be minimum at
→