Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

Multiple choice audible, infra and ultra sound with its application study of sound physics

A pendulum vibrates with a time period of 1 second. What kind of sound is produced by it?

  1. Supersonic

  2. Audible

  3. Infrasonic

  4. Ultrasonic
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The low frequency vibration of infrasonic wave is less than $20\,Hz$. The pendulum vibrates at this low frequency with a time period of $1$ second.

Multiple choice audible, infra and ultra sound with its application study of sound physics

How are bats able to fly in the dark?

  1. They produce infrasonic waves.

  2. They can hear ultrasonic sounds.

  3. They produce infrared waves.

  4. They can hear infrared waves.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Bats emit ultrasonic sound waves which bounces back from the objects and enables them to sense an obstruction and also hunt for prey.

Multiple choice audible, infra and ultra sound with its application study of sound physics

Which of the following frequency of sound can't be heard by human beings?

  1. 5 Hz

  2. 100 Hz

  3. 500 Hz

  4. 1000 Hz
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The generally accepted standard range of audible frequencies is 20 to 20,000 Hz, although the range of frequencies individuals hear is greatly influenced by environmental factors. Frequencies below 20 Hz are  generally felt rather than heard, assuming the amplitude of the vibration is great  enough. So 5 and 10 Hz both can't be heard by human ear in general.

Multiple choice audible, infra and ultra sound with its application study of sound physics

What is frequency of  the sound of vibrations of pendulum which we can't hear?

  1. below 20 Hz

  2. above 20 Hz

  3. 20 Hz

  4. none of these.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The frequency of a vibrating pendulum is quite small and less than 20 Hz which is not in the audible range. Hence, it is not heard.

Multiple choice audible, infra and ultra sound with its application study of sound physics

Which of the following frequency of sound can't be heard by human beings?

  1. 40 Hz

  2. 400 Hz

  3. 4000 Hz

  4. 40,000 Hz
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The generally accepted standard range of audible frequencies is 20 to 20,000 Hz, although the range of frequencies individuals hear is greatly influenced by environmental factors. Frequencies below 20 Hz are generally felt rather than heard, assuming the amplitude of the vibration is great enough. So sound with frequency 40,000 Hz can't be heard by human ear in general.

Multiple choice audible, infra and ultra sound with its application study of sound physics

We are able to hear the sounds made by a source, if the frequency of sound is :

  1. Within audible range in air

  2. Within audible range in vacuum

  3. Within audible range in water
  4. Within audible range in $CO _2$
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

sound needs a medium to travel and to hear a sound it should be in audible range in any medium.

so the answer is A, C and D.

Multiple choice audible, infra and ultra sound with its application study of sound physics

Which is not the condition for hearing sound?

  1. There must be a vibrating body capable of transferring energy.

  2. There must be a material medium to pick up and propagate energy

  3. The medium must have a large density.

  4. There must be receiver to receive the energy and interpret it.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Dense molecules vibrate at slower speeds. The more dense the string is, the slower it will vibrate, and the lower its frequency will be. Instruments often have strings made of different materials. The strings used for low pitches will be made of a more dense material than the strings used for high pitches. 
The more dense the medium the slower the speed of sound. For example steel is 6000 times more denser than air but 2,000,000 times more elastic than air, so sound travels 16 times faster in steel than in air. 

Multiple choice audible, infra and ultra sound with its application study of sound physics

Which of the following statement is/are true in case of waves ?

  1. Transverse vibrations are set on the string of a guitar.
  2. As compared to light, a sound wave produced on the moon will take a time about $10^6$ times longer to reach the earth.

  3. A sound note of wavelength 1 cm in air cannot be heard by a man.

  4. Sound travels faster in water than in air.
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

(A) When a guitar string is struck , string is disturbed and the medium (string) particles vibrate perpendicular to the direction of motion disturbance , therefore transverse vibrations are set on the guitar string . -True

(B) Sound wave are longitudinal mechanical waves , which require a medium to travel as there is no medium on moon , so they cannot travel there and can't reach to earth . Whereas light waves ,being electromagnetic waves can travel to earth . -False
(C) If wavelength $\lambda=1cm=0.001m$ and $v=332m/s$ ,
then frequency $f=v/\lambda=332/0.001=332000Hz$ ,
that is an ultrasonic frequency which cannot be heard by a man . -True
(D) Sound travels faster in liquid than gases due to higher elasticity of liquids , therefore sound travels faster in water than in air .  -True