Questions

The third and longest period of prenatal development, extending from the ninth week until birth is Fetal period.

The process of prenatal development occurs in three main stages. The first two weeks after conception are known as the germinal stage, the third through the eighth week are known as the embryonic period, and the time from the ninth week until birth is known as the fetal period.

A standing wave also known as a stationary wave, is a wave in which its peaks or any other point on the wave do not move spatially.

This phenomenon can occur because the medium is moving in the opposite direction to the wave, or it can arise in a stationary medium as a result of interference between two waves traveling in opposite directions. The most common cause of standing waves is the phenomenon of resonance, in which standing waves occur inside a resonator due to interference between waves reflected back and forth at the resonator's resonant frequency.

Hence, standing wave occurs when a wave reflects upon itself.

The distance in pitch between any two tones is called an interval.