Bissoy.com
Doctors Medicines MCQs Q&A

In any function where microphone, amplifier and speakers are used often one would hear a humming sound, which increases in volume gradually. This is due to:

In any function where microphone, amplifier and speakers are used often one would hear a humming sound, which increases in volume gradually. This is due to: Correct Answer Positive feedback between microphone and speaker

  • A simple public address system consists of a microphone, an amplifier, and one or more speakers.
  • Whenever you have those three components, you have the potential for feedback.
  • Acoustic feedback or feedback course when the sound from the speakers makes if it back into the microphone and is re-amplified and sent through the speakers again.
  • This loop happens so quickly that it creates its frequency, which we hear as a humming sound.
  • This happens due to positive feedback between the microphone and the speaker. 

Related Questions

In the following figure, square represents Hindi speakers, triangle represents Tamil speakers, circle represents Marathi speakers and rectangle represents English speakers. Which set of letters represents English speakers who do not speak Hindi and Tamil speakers who do not speak English?
Four 8 Ω speakers are connected in parallel to the output of an audio amplifier. If the maximum voltage to the speakers is 12 V, the amplifier must be able to deliver to the speakers
Question : How many speeches were delivered in the two days' programme ?

Statements :
I. 18 speakers were invited to give at least one speech (maximum of two speech), out of which one-sixth of the speakers could not come.
II. One-third of the speakers gave two speeches each.
Read the passage carefully and choose the best answer to each question out of the four alternatives and click the button corresponding to it. Awareness means the capacity to see a coffee pot and hear the birds sing in one's own way, and not the way one was taught. It may be assumed on good grounds that seeing and hearing have a different quality for infants than for grownups and that they are more aesthetic and less intellectual in the first years of life. A little boy sees and hears birds with delight. Then the 'good father' comes along and feels he should 'share' the experience and help his son 'develop'. He says, "That's a jay and this is a sparrow." The moment the little boy is concerned with which is a jay and which is a sparrow, he can no longer see the birds or hear them sing. He has to see and hear them the way his father wants him to. Father has good reasons on his side: since few people can afford to go through life listening to the birds sing, sooner the little boy starts his 'education' the better. Maybe he will be an ornithologist when he grows up.
What would the 'good father' do?
The statements given below are followed by two conclusions labeled I and II. Assuming that the information in the statement is true, even if it appears to be at variance with generally established facts, decide which conclusion(s) logically and definitely follow(s) from the information given in the statements. Statements: All Cars are Speakers. Some Speakers are Windows. Conclusions: I. Some Cars are Windows II. Some Windows are Speakers.
Read the given statement and conclusions carefully and decide which of the conclusions logically follow(s) from the statement. Statement: Sound cannot travel in vacuum. Conclusions: I. We cannot hear sound of explosion in vacuum. II. We cannot hear sound of explosion in atmosphere
In the following question, sentences of a paragraph have been jumbled and labelled as A, B, C and D. You are required to rearrange the jumbled sentences of the paragraph and mark your response accordingly by selecting the correct option. A: As the source continues to vibrate the medium, the vibrations propagate away from the source at the speed of sound, thus forming the sound wave. B: The sound source creates vibrations in the surrounding medium.  C: The sound waves are generated by a sound source, such as the vibrating diaphragm of a stereo speaker. D: Sound can propagate through a medium such as air, water, and solids as longitudinal waves and also as a transverse wave in solids.
Read the passage carefully and choose the best answer to each question out of the four alternatives and click the button corresponding to it. Awareness means the capacity to see a coffee pot and hear the birds sing in one's own way, and not the way one was taught. It may be assumed on good grounds that seeing and hearing have a different quality for infants than for grownups and that they are more aesthetic and less intellectual in the first years of life. A little boy sees and hears birds with delight. Then the 'good father' comes along and feels he should 'share' the experience and help his son 'develop'. He says, "That's a jay and this is a sparrow." The moment the little boy is concerned with which is a jay and which is a sparrow, he can no longer see the birds or hear them sing. He has to see and hear them the way his father wants him to. Father has good reasons on his side: since few people can afford to go through life listening to the birds sing, sooner the little boy starts his 'education' the better. Maybe he will be an ornithologist when he grows up.
What does the writer mean by 'awareness'?
Read the passage carefully and choose the best answer to each question out of the four alternatives and click the button corresponding to it. Awareness means the capacity to see a coffee pot and hear the birds sing in one's own way, and not the way one was taught. It may be assumed on good grounds that seeing and hearing have a different quality for infants than for grownups and that they are more aesthetic and less intellectual in the first years of life. A little boy sees and hears birds with delight. Then the 'good father' comes along and feels he should 'share' the experience and help his son 'develop'. He says, "That's a jay and this is a sparrow." The moment the little boy is concerned with which is a jay and which is a sparrow, he can no longer see the birds or hear them sing. He has to see and hear them the way his father wants him to. Father has good reasons on his side: since few people can afford to go through life listening to the birds sing, sooner the little boy starts his 'education' the better. Maybe he will be an ornithologist when he grows up.
How do children perceive things around them?
Read the passage carefully and choose the best answer to each question out of the four alternatives and click the button corresponding to it. Awareness means the capacity to see a coffee pot and hear the birds sing in one's own way, and not the way one was taught. It may be assumed on good grounds that seeing and hearing have a different quality for infants than for grownups and that they are more aesthetic and less intellectual in the first years of life. A little boy sees and hears birds with delight. Then the 'good father' comes along and feels he should 'share' the experience and help his son 'develop'. He says, "That's a jay and this is a sparrow." The moment the little boy is concerned with which is a jay and which is a sparrow, he can no longer see the birds or hear them sing. He has to see and hear them the way his father wants him to. Father has good reasons on his side: since few people can afford to go through life listening to the birds sing, sooner the little boy starts his 'education' the better. Maybe he will be an ornithologist when he grows up.
What does an Ornithologist study?