A tuning fork vibrating with a sonometer having 20 ~cm wire produ… - Vidyadip

MCQ

A tuning fork vibrating with a sonometer having $20 \mathrm{~cm}$ wire produces 5 beats per second. The beat frequency does not change if the length of the wire is changed to $21 \mathrm{~cm}$. the frequency of the tuning fork (in Hertz) must be

A
$200$
B
$210$
✓
$205$
D
$215$

✓

Answer

Correct option: C.

$205$

Let the frequency of tunning fork be $N$As the frequency of vibration string $\propto \frac{1}{\text { lengthofstring }}$
For sonometer wire of length $20 \mathrm{~cm}$,frequency must be $(N+ 5)$ and that for the sonometer wire of length $21 \mathrm{~cm}$,the frequency must be $(N-5)$ as in each case the tunning fork produces $5$ beats/sec with so no meterwire
Hence $n_1 l_1=n_2 l_2 \Rightarrow(N+5) \times 20=(N-5) \times 21$
$\Rightarrow N=205\mathrm{~Hz} \text {. }$

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 "MCQ" from Waves and Sound→Waves and Sound — all question types→JEE physics STD 12 Science question papers→CBSE Board STD 12 Science question papers→CBSE Board question paper generator→

Similar questions

The resultant of two forces, one double the other in magnitude, is perpendicular to the smaller of the two forces. The angle between the two forces is

A stick of $1 m$ is moving with velocity of $2.7 \times 10^8 ms ^{-1}$. What is the apparent length of the stick $\left(c=3 \times 10^8 ms ^{-1}\right)$

The amplification factor of a triode is $20$ and trans-conductance is $3$ milli mho and load resistance $3 \times 10^4\ \Omega$, then the voltage gain is

The wave theory of light was given by

A galvanometer has a coil of resistance $100\, ohm$ and gives a full scale deflection for $30\, mA$ current. If it is to work as a voltmeter of $30\, volt$ range, the resistance required to be added will be.....$Ω$

Which one of these is non-divisible

The speed of a wave in a certain medium is $960 \mathrm{~m} / \mathrm{s}$. If $3600$ waves pass over a certain point of the medium in $1$ minute, the wavelength is

A magnetised wire of moment $M$ is bent into an arc of a circle subtending an angle of $60^o$ at the centre; then the new magnetic moment is

A heavy steel ball of mass greater than $1 \mathrm{~kg}$ moving with a speed of $2 \mathrm{~m} \mathrm{sec}^{-1}$ collides head on with a stationary ping-pong ball of mass less than $0.1 \mathrm{gm}$. The collision is elastic. After the collision the pingpong ball moves approximately with speed

A brick of mass $2 \mathrm{~kg}$ begins to slide down on a plane inclined at an angle of $45^{\circ}$ with the horizontal. The force of friction will be