Tag: physics

Questions Related to physics

Which of the following is/are  percussion instruments?

physics world of sounds sound is produced by a vibrating body propagation of sound production and propagation of sound

  1. Bell

  2. cymbals

  3. drum

  4. All of the above

Show answer
Correct Option: D
Explanation:

Percussion instruments are those which are played by hitting on the membrane of that instrument. They include instruments such as tabla, bell drum, cymbals etc.

Which of the following is the vibrating part of Banjo?

physics world of sounds sound is produced by a vibrating body propagation of sound production and propagation of sound

  1. Stretched- Membrane

  2. Stretched- String

  3. Air column

  4. None of the above

Show answer
Correct Option: B
Explanation:

String instruments are those which are played by manually vibrating the strings made of metal. When these strings are made to vibrate they emit a sound of a specific tone and produce music. Examples of such instruments are Banjo, guitar,  violin and so on. 

Assuming that the period of vibration of a tuning fork depends upon the length $l$ of its prongs density $\rho$ of its material and the elastic constant  $E$ of its material what would be the formula for the period of its vibration.

physics world of sounds sound is produced by a vibrating body propagation of sound production and propagation of sound

  1. $\frac{k}{l}\sqrt{\frac{y}{d}}$

  2. $\frac{2k}{l}\sqrt{\frac{y}{d}}$

  3. $\frac{k}{2l}\sqrt{\frac{2y}{d}}$

  4. $\frac{3k}{l}\sqrt{\frac{y}{2d}}$

Show answer
Correct Option: A
Explanation:

Considering $n=k{l}^{a}{d}^{b}{y}^{c}$--------(A) 

where k=dimensionless quantity 
l=length $=L$;  d=density$=kg/{m}^{3}$ and y=Young modulus$=kg/m{s}^{2}$
Substituting the above mentioned dimension in A we get,
$[{T]}^{-1}=[{L]}^{a}[{M{L}^{-3}]}^{b}[{M{L}^{-1}{T}^{-2}]}^{c}$
Comparing the power of $ML$  and $T$ we have,
$b+c=0$---------(1)
$a-3b-c=0$------(2)
$-2c=-1$
$c=\dfrac{1}{2}$
Putting the values of c in 1 we get,
$b=\dfrac{-1}{2}$
 Putting the values of b and c in 2 we get,
$a=-1$
Thus putting the values of a,b and c in A we get,
$n=k{l}^{-1}{d}^{1/2}{y}^{1/2}=\dfrac{k}{l}\sqrt{\dfrac{y}{d}}$ 

Match the following and choose the correct answer.

A String vibration 1 Tabla
B Membrane vibration 2 Bicycle bell
C Vibration of air 3 Sitar
D Vibration of plate 4 Flute
physics world of sounds sound is produced by a vibrating body propagation of sound production and propagation of sound

  1. A-1, B-2, C-3, D-4

  2. A-2, B-1, C-4, D-3

  3. A-3, B-1, C-4, D-2

  4. A-4, B-3, C-2, D-1

Show answer
Correct Option: C
Explanation:

String vibration is there in sitar.

Membrane vibration is there in tabla.
Vibration of air is in flute.
Vibration of plate is in bicycle bell.

The membrane of a drum vibrates to produce sound. Similarly the string of a sitar vibrates to produce sound. Based on these two examples answer the following question. Which part of a whistle vibrates to produce sound?

physics world of sounds sound is produced by a vibrating body propagation of sound production and propagation of sound

  1. Body of whistle

  2. Air

  3. Mouth of the person

  4. All of the above

Show answer
Correct Option: A
Explanation:

A body of whistle is responsible for the whistle to produce sound.

As air enters the whistle at one end.As the air reaches the other, closed end, all the air molecules fill up on top of each other and cause a high pressure region.The air escapes out the little hole in the end making a sound you hear.The frequency of sound depends on the length of the whistle.

Percussion instruments are musical instruments that are played by

physics world of sounds sound is produced by a vibrating body propagation of sound production and propagation of sound

  1. banging

  2. shaking

  3. both A and B

  4. hitting

Show answer
Correct Option: C
Explanation:

Percussion instruments are musical instruments that are played by banging and shaking both.

so the answer is C.

If we strike a water-filled bowl with spoon, then why there is variation in the sound produced due to change in water level of the bowl?

physics world of sounds sound is produced by a vibrating body propagation of sound production and propagation of sound

  1. due to change in pitch

  2. due to change in amplitude

  3. both A and B

  4. None of the above

Show answer
Correct Option: A
Explanation:

Due to change in air column the wavelength and fundamental frequency changes. So the pitch of the sound changes which results in difference in the produced sounds .

so the answer is A.

Name the instruments for which more than one part is responsible for the production of sound.

physics world of sounds sound is produced by a vibrating body propagation of sound production and propagation of sound

  1. Tabla

  2. Violin

  3. Guitar

  4. All of the above

Show answer
Correct Option: A
Explanation:

In violin and guitar, only the string is responsible for sound production. Whereas in Tabla, the diaphragm, as well as the air in the Tabla, produce sound.

Two capacitors of $1\mu F$ and $2\mu F$ are connected in series and this combination is changed upto a potential difference of $120$ volt. What will be the potential difference across $1 \mu F$ capacitor:

physics capacitance capacitors in series combination of capacitors capacitors in parallel and series

  1. $40 volt$

  2. $60 volt$

  3. $80 volt$

  4. $120 volt$

Show answer
Correct Option: C
Explanation:
Given, $c _1=1\mu f,c _2=2\mu f,PD=120v$

$C _{eq}=\dfrac{c _1c _2}{c _1+c _2}=\dfrac{2\times1}{2+1}=\dfrac{2}{3}\mu f$

We know,  $Q=cv$ Where Q is the charge, C is the capacitance of the capacitor and v is the potential difference.

Now, $Q _{net}$ in circuit is equivalent capacitance of capacitors attached in the circuits is multiplied by PD

$Q _{net}=12\times\dfrac{2}{3}=80$

$Q=cv=1\mu fv=80\Rightarrow v=80v$

Three long concentric cylindrical shells have radii R, 2R and $2\sqrt{2}R$. Inner and outer shells are connected to each other. The capacitance across middle and inner shells per unit length is:

physics capacitance capacitors in series combination of capacitors capacitors in parallel and series

  1. $\dfrac{\dfrac{1}{3}\epsilon _0}{ln 2}$

  2. $\dfrac{6\pi \epsilon _0}{ln 2}$

  3. $\dfrac{\pi \epsilon _0}{2 ln 2}$

  4. None

Show answer
Correct Option: B