SSC CGL 2017 Pre exam in scheduled in the month of June/July 2017. At SA, We are providing to you the NOTES ON GENERAL SCIENCE, these notes will help you build your basic understanding of all topics and you’ll be able to score maximum marks in SSC CGL Pre exam. Study, Revise and Learn all these notes by heart.
The speed of sound in a medium depends:
- temperature of the medium.
- pressure of the medium.
The velocity of sound through a gas is inversely proportional to the square root of the density of the gas.
- It is a reflection of sound that arrives at the listener with a delay after the direct sound.
- The sensation of sound persists in our brain for about 0.1 second.
- To hear a distinct echo, the time interval between the original sound and the reflected one must be at least 0.1 second.
- For hearing distinct echoes, the minimum distance of the obstacle from the source of sound must be 17.2 m. This distance will change with the temperature of air. Echoes may be heard more than once due to successive or multiple reflections.
The phenomenon of prolongation of sound due to successive reflections of sound from surrounding objects is called reverberation.
In stethoscopes the sound of the patient’s heartbeat reaches the doctor’s ears by multiple reflection of sound.
The audible range of sound for human beings extends from about 20 Hz to 20000 Hz (one Hz = one cycle/s). Children under the age of five and some animals, such as dogs can hear up to 25 kHz (1 kHz = 1000 Hz).
To be continued…