The Solid State

Question 89
CBSEENCH12005437

What are extrinsic semi-conductor?

Solution
An extrinsic semiconductor is an improved intrinsic semiconductor with a small amount of impurities added by a process, known as doping, which alters the electrical properties of the semiconductor and improves its conductivity. Introducing impurities into the semiconductor materials (doping process) can control their conductivity.
Question 90
CBSEENCH12005438

What is Photovoltaic.

Solution
Photovoltaics (PV) is a method of generating electrical power by converting solar radiation into direct current electricity using semiconductors that exhibit the photovoltaic effect. Example-amorphous silica.
Question 91
CBSEENCH12005439

Although pure silicon is an insulator, then how does it behave as a semiconductor on heating.

Solution
On heating some covalent bonds among silicon atoms break on heating and electrons become free to move under applied field, hence silicon behaves like semi-conductor at high temperature.
Question 92
CBSEENCH12005440

What is meant by tetrahedral void in a close-packed structure?

Solution
 It is the empty space between three spheres in one layer and one sphere in the layer above it or one sphere in the layer below it is called a tetrahedral void
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