56. Under the influence of electric field, which of the following statements is true about the movement of electrons and holes in a p-type semiconductor?
(i) Electron will move towards the positively charged plate through electron holes.
(ii) Holes will appear to be moving towards the negatively charged plate.
(iii) Both electrons and holes appear to move towards the positively charged plate.
(iv) Movement of electrons is not related to the movement of holes.
56. Under the influence of electric field, which of the following statements is true about the movement of electrons and holes in a p-type semiconductor?
(i) Electron will move towards the positively charged plate through electron holes.
(ii) Holes will appear to be moving towards the negatively charged plate.
(iii) Both electrons and holes appear to move towards the positively charged plate.
(iv) Movement of electrons is not related to the movement of holes.
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1 Answer
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56. Options (i) and (ii) are correct since Si or Ge of group-14 are doped with electron deficient impurity i.e., group-13 elements like B, Al, or Ga containing only three valence electrons and hence is called as p-type semiconductors while the electron holes are created whenever an atom of such trivalent metal gets bonded with three of its neighbouring tetravalent silicon or germanium atoms.
The fourth valence electron of Ge or Si moves through the holes and under the influence of the electric field electrons move towards the positively charged plate through these holes. But it would appear as if the electron holes are posit
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75. Option (iii) Assertion is the correct statement, but the reason is wrong is the answer since besides the body centre there is one octahedral void at the centre of each 12 edges which is shared between four adjacent unit cells. Thus, Octahedral voids present at the body centre of the cube = 1
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74. Option (ii) Assertion and reason both are correct statements, but reason is not correct explanation for assertion is the answer since in graphite carbon atoms are arranged in different layers and each atom is covalently bonded to three of its neighbouring atoms in the same layer due to which the fourth valence electron of each atom, present between the different layers is free to move and this makes graphite a good conductor of electricity.
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