Era is divided into period but what are periods again divided into ?

Each period is divided into .........

A loaded spring vibrates with a period T. The spring is divided into four equal parts and the same load is divided into four equal parts and the same load is suspended from one end of these parts. The new period is

What is meant in the periodic table by a period ?

The long form of the periodic table is divided into ______ blocks

A cylindrical wavefront is divided into number of Fresnel.s half period elements. With the increase of the order of the element, the area of the element