Tag: physics

Questions Related to physics

Why do distant sounds such as those of traffic and loudspeakers become louder during the night time than during the day time?

physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

  1. Due to the reflection of sound waves.

  2. Due to the refraction of sound waves.

  3. Due to the absence of other sounds.

  4. Due to a clear perception of hearing.

Show answer
Correct Option: A
Explanation:

Sound waves travel differently at night than during the day. During the day, the sound bends away from the ground;during the night, it bends towards the ground. 

In an unoccupied hall of a choultry you will experience the echo effect of sound. If the same hall is furnished with almirahs, tables, chairs,and other commodities, you may not experience the echo clearly. It is because, 

physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

  1. Sound waves get absorbed by the objects in the hall.

  2. The area of reflecting surface decreases.

  3. Reflected sound is reflected again.

  4. Sound does not get reflected again.

Show answer
Correct Option: A
Explanation:

echo is heard due to reflection of sound and if obstacles are placed in path of sound then they will either absorb sound or will not perfectly reflect sound as before so echo will be not effective one .

so the answer is A.

The persistence of sound in a closed enclosure, due to continuous reflections at the walls, even after the source has stopped producing sound is known as

physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

  1. The persistence of hearing

  2. An echo

  3. Reverberation

  4. The ultra sounds

Show answer
Correct Option: C
Explanation:

Reverberation is the phenomenon of persistence of sound in a closed enclosure, due to multiple reflection of sound from the walls, even after the source has stopped producing sound. The intensity of sound gets reduced after each reflection.

Select the instrument that works on the principle of multiple reflection of sound.

physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

  1. Watthour meter

  2. Sonar

  3. Stethoscope

  4. Decibel meter

Show answer
Correct Option: C
Explanation:

The sound of a heartbeat ( or lungs ) reaches the doctor's ears by the multiple reflections of sound waves though the stethoscope tube.

Perforated card boards are used in halls, for

physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

  1. reflection of sound

  2. absorption of sound

  3. refraction of sound

  4. as a decorative material

Show answer
Correct Option: B
Explanation:

Perforated card boards are used for the absorption of sound, as they are good sound absorbents and decrease reverberation time. 

For good absorption of sound in auditorium it requires

physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

  1. a few windows to be opened

  2. all closed windows

  3. maps hanging from walls

  4. hanging light curtains.

Show answer
Correct Option: A
Explanation:

A few window should be kept opened for the good absorption of sound in auditorium. Because if we open few windows, more sound will absorbed and more will be the sound clarity and better sound effect can be experienced. 

In an auditorium the big curtain when falls suddenly then the reverberation time

physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

  1. increases

  2. decreases

  3. Remains same

  4. becomes zero

Show answer
Correct Option: B
Explanation:

The reverberation time will get decreased because curtain will abrosh the sound and more sound will get abrashed then the earlier.  

Which of the following has largest absorption coefficient?

physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

  1. heavy curtain

  2. cork

  3. marble

  4. open window

Show answer
Correct Option: D
Explanation:

The absorption coefficient of a body is the ratio of the heat radiation absorbed by the body to the total heat radiation incident on it. Since an open window can allow all the radiation into it, it is a good absorber. Hence its coefficient is highest.

Upholstered seats in cinema halls are arranged for

physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

  1. absorption of sound

  2. reflection of sound

  3. diffraction of sound

  4. to hear an echo

Show answer
Correct Option: A
Explanation:

Upholstered seats in cinema halls are arranged for better absorption of sound and to decrease the reverberation time. 

The total absorption of a volume $12000 m^3$ is equal to $1000 m^2$ in the units of an open window. Total absorption of the hall is increased to $2000m^2$ due to entry of audience. The change in its reverberating time is

physics study of sound reverberation applications of reflection of sound multiple reflection of sound and reverberation applications of ultrasound

  1. $1s$

  2. $2s$

  3. $3s$

  4. $4s$

Show answer
Correct Option: A