What are holes in a semiconductor?

What are holes in semiconductor?

A hole in a semiconductor is

If the ratio of the concentration of electron to that of holes in a semiconductor is (7)/(5) and the ratio of current is (7)/(4) then what is the ratio of their drift velocities ?

If the ratio of the concentration of electron to that of holes in a semiconductor is (7)/(5) and the ratio of currect is (7)/(4) then what is the ratio of their drift velocities ?

What is a hole in semiconductor?

Explain formation of holes in a semiconductor.

What do you understand by term 'holes' in a semiconductor? Discuss how they move under the influence of an electric field?