Page 102 - Physics - XII
P. 102

VIVA VOCE




               Q1.  What is an intrinsic semiconductor?
              Ans.  A pure semiconductor material is known as an intrinsic semiconductor.

               Q2.  What is an extrinsic semiconductor.
              Ans.  When  some  impurity  is  added  in  a  controlled  manner  in  a  pure  semiconductor,  it  is  called  an
                     extrinsic semiconductor.

               Q3.  What is n-type semiconductor?
              Ans.  When a very small quantity of pentavalent impurity is added to a pure semiconductor, it is called
                     n-type semiconductor.

               Q4.  Give the name of two types of biasing.
              Ans.  (i) Forward biasing (ii) Reverse biasing

               Q5.  When is a p-n junction forward biased?
              Ans.  When p-region is at a higher potential as compared to n-region, p-n junction is said to be forward
                     biased.

               Q6.  Name four pentavalent impurities.
              Ans.  The pentavalent impurities are: (i) Phosphorus (ii) Arsenic (iii)Antimony (iv) Bismuth.
               Q7.  What is a p-type semiconductor?
              Ans.  A  p-type  semiconductor  is  obtained  by  adding  a  very  small  quantity  of  trivalent  impurity  in  a
                     controlled manner to a pure semiconductor.

               Q8.  Name fi ve trivalent impurities.
              Ans.  The trivalent impurities are: (i) Boron (ii) Aluminium (iii) Gallium (iv) Indium (v) Thalium.

               Q9.  What is biasing of p-n junction diode?
              Ans.  When a p-n junction is connected across a source of potential diff erence, it is said to be biased.
               Q10.  When is a p-n junction reverse biased?
              Ans.  When p-region is at a lower potential as compared to n-region, p-n junction is said to be reverse
                     biased.

               Q11.  How does the bias aff ect the thickness of the depletion layer?
              Ans.  Forward bias decreases the thickness of depletion layer while reverse bias increases the thickness of
                     depletion layer.
               Q12.  What is the reverse saturation current?
              Ans.  The constant reverse current fl owing through the diode due to the reverse bias voltage is called
                     reverse saturation current.


               Q13.  Name the diff erent types of materials.
              Ans.  Diff erent types of materials: 1. Conductors 2. Semiconductors 3. Insulators
               Q14.  Name the two semiconductor materials.
              Ans.  Germanium (Ge) and Silicon (Si)




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