Ans. The vocal cords in men are about 20mm long. In women these are about 5mm shorter.
Ans. The working of a toy telephone tells us that sound travels through solid substances.
Ans. Usually the voice of a woman has a higher frequency and therefore, produces a sound of higher pitch.
Ans. Frequency, amplitude and frequency are the three characteristics which are used to describe oscillations.
Ans. Musical sound is one which is pleasing to the ear. Sound produced by a harmonium is a musical sound.
Ans. Presence of excessive or unwanted sounds in the environment is called noise pollution.
Ans. The maximum displacement of a vibrating object from its central position is called the amplitude of oscillation.
Ans. Ultrasound cannot be heard by humans because the ultrasound equipment works at frequencies higher than 20,000 Hz.
Ans. A sound cannot be heard on the moon because on the moon there is no medium such as air though which the vibrations can propagate.
Ans. We must never put a sharp, pointed or hard thing into our ear. It can damage the eardrum. The damaged eardrum can impair hearing.
Ans. When we strike the membrane of a mridangam, the sound that we hear is not only that of the membrane but of the whole body of the instrument.
Ans. Time Period given by the inverse of the frequency.
Time Period = 1/frequency
Ans. (i) The sound will become loud on increasing the amplitude.
(ii) The sound will become shrill on increasing the frequency.
Ans. Frequency = (Number of Oscillations)/Time = 40/4 = 10 Hz
Time period = 1/(Frequency of Oscillation) = 1/10 = 0.1 sec
Ans. Speed of the light is more than the speed of sound. Thus, Lightning is seen earlier and thunder is heard later.
Ans. Solid: Metal (Iron, Steel, Aluminium), wood, bricks etc.
Ans. The voice of a baby has a higher frequency (or higher pitch) than that of a woman due to which the voice of a baby is even more shrill than that of a woman.
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