Sound (Physics)

Total Questions: 56

51. The basic units of sound are called [U.P.P.C.S. (Mains) 2017]

Correct Answer: (b) Phonemes
Solution:

Phonemes is the basic unit of sound (phonology). It is the smallest unit of sound that may cause a change of meaning within a language, but that does not have meaning by itself.

52. Assertion (A): Reverberation mainly feels in large churches and in other large buildings. [U.P. Lower Sub. (Spl.) (Pre) 2002-003]

Reason (R): The walls, roof and ground may cause multiple sound reflections.

Code:

Correct Answer: (a) Both (A) and (R) are true, and (R) is the correct explanation of (A).
Solution:

Reverberation is a result of multiple reflections. A sound wave in an enclosed or semi-enclosed environment (like large church or in other big building) will be broken up as it is bounced back and forth among the reflecting surfaces.

Reverberation is an effect which is multiplicity of echoes whose speed of repetition is to be quick for them and to be perceived as separate from one another.

53. Consider the following statements: [I.A.S. (Pre) 2008]

1. A widely used musical scale called diatonic scale has seven frequencies.

2. The frequency of the tone Sa is 256 Hz and that of Ni is 512 Hz.

Which of the statements given above is/are correct?

Correct Answer: (d) Neither 1 nor 2
Solution:

The most common musical scale is the diatonic scale. It consists of a series of eight notes or tones, and the ratio between the last and the first note is 2 : 1. It is therefore called an octave.

The major diatonic scale consists of notes with frequencies in the ratio 1, 9/8, 5/4, 4/3, 3/2, 5/3, 15/8 and 2 relative to a key note. The series of notes is defined as:

CDEFGABC₁
(Sa)(Re)(Ga)(Ma)(Pa)(Dha)(Ni)(Sa₁)

Here, the higher frequency Sa (Sa₁) is called the octave of the lower Sa. If the frequency of first note (Sa) is set as 256 Hz, then that of note Ni is 480 Hz (256 × 15/8) and the frequency of octave Sa₁ is 512 Hz. The above explanation shows that both the given statements are incorrect.

54. When T.V. is switched on: [U.P.P.C.S. (Pre) 2007]

Correct Answer: (a) Audio and video both start simultaneously
Solution:

When T.V. is switched on, audio and video start simultaneously. In old models of television, audio was heard immediately but the video starts as it needs some warm up time. But in modern televisions, audio synchronizer is used to correct this sync error.

55. In television broadcast, the picture signals are transmitted by - [R.A.S./R.T.S. (Pre) 2012]

Correct Answer: (a) Amplitude modulation
Solution:

In a television broadcast, the picture signals are transmitted by amplitude modulation and audio signals are transmitted by frequency modulation.

56. The technique used to transmit audio signals in television broadcast is - [U.P.U.D.A./L.D.A. (Spl.) (Pre) 2010]

Correct Answer: (c) Frequency modulation
Solution:

In a television broadcast, the picture signals are transmitted by amplitude modulation and audio signals are transmitted by frequency modulation.