The scientists classified the elements according to their properties to facilitate their study and to find a relationship between the elements, and their chemical and physical properties. The modern periodic table was developed by...
The sound waves The human ear differentiates between the sounds that reach it through the different factors which are the sound pitch, the sound intensity and the sound quality. The sound pitch The sound...
Sound waves There are two types of sound waves which are the audible sounds and the non-audible sounds, The audible sounds such as the sonic waves, and the non-audible sounds such as the ultrasonic...
The sound The sound is an external factor that affects the ear causing the sense of hearing. and it is produced due to the vibration of the bodies and it stops when the vibrating...
