Asked/Added Questions From NCERT:

1) The direction in which the sound is incident and the reflected make equal angles.

2) The angle of incidence, angle of reflection and the normal to the reflecting surface are in the same plane.

-Answered by priyanshu kumar On 05 October 2019:03:27:30 PM

1) Ultrasound is generally used to clean parts located in hard to reach places. For example Spiral tube, odd shaped parts electronic components etc.

2) Ultrasound can be used to detect cracks and flaws in metal blocks.

3) Ultrasound is used in the medical field to detect illness diseases.

4)  Ultrasound is used in a device named SONAR which is used to measure the depth of ocean in the ships.

5) Ultrasound are used extensively in industries and for medical purpose.

6) Ultrasound are highly frequency waves.

-Answered by priyanshu kumar On 05 October 2019:03:33:18 PM

 It is voice box in humans That produces sound.

-Answered by Gunnaj sheikh On 27 April 2019:07:21:33 PM

 The frequency of oscillation is expressed in terms of hertz its symbol is hz. A frequency of one hz is one oscillation per second.

-Answered by priyanshu kumar On 26 April 2019:08:16:45 AM

I cannot hear any sound on the computer

 If you cannot hear any sounds on your computer, for example when you try to play ... that you have not muted the application that you are using to play sound

-Answered by Sohail alam On 26 April 2019:08:15:47 AM

 Yes I feel don't hear the sound.

-Answered by priyanshu kumar On 26 April 2019:08:43:30 AM