Questions

Semiconductors are those materials that are neither good conductors nor the good insulators of heat and electricity. Silicon (Si), Germanium (Ge) and Cadmium Sulphide (CdS) are semiconductors which work as conductors in some special conditions only.

A candidate key is a column, or set of columns, in a table that can uniquely identify any database record without referring to any other data. Each table may have one or more candidate keys, but one candidate key is unique, and it is called the primary key.

For balancing the weight of ring, you need to put your finger or any solid object inside the ring so that you will be able to sustain their own weight because they are not able to sustain their own weight.so its centre of mass lies outside the body.