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The Pearson Question Bank for Electronics and Communication Engineers

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The Pearson Question Bank for Electronics and Communication Engineers is a comprehensive study aid designed to help students preparing for examinations in electronics and communication engineering. It contains a vast collection of practice questions that cover all the major topics of the subject. The question bank includes questions of varying difficulty levels, which can help students to assess their understanding of the subject and identify areas where they need more practice. The questions are organized according to the syllabus of various universities and engineering colleges, making it easier for students to focus on the relevant topics

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The Pearson Question Bank
for
Electronics and Communication
Engineers
(PSUs/GATE/IES)

, 1
CHAPTER
MATERIALS AND
COMPONENTS

 x Spin quantum number ms FORFNZLVHDQWLFORFNZLVH
1.1 STRUCTURE AND PROPERTIES OF 1 1
ELECTRICAL ENGINEERING MATERIALS  x ms  ,
2 2

Electronic Energies in an Atom of an Element $VROLGLQZKLFKWKHDWRPVDUHDUUDQJHGLQDUHJXODUSHULRGLF
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The electron bound to the nucleus of an atom can exist only in form an array in space. This array of points is called a Crystal
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According to Bohr’s theory of the atom crystalline solid and is called the lattice constant d of the crystal.

2 S 2 me e 4 13.6
En eV;
n2 h2 n2 Principles of Electron Energy Bands
eV electron volt
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ber n, l , m1 and ms RIWKHVDPHPDJQLWXGHDQGGLUHFWLRQLHQRW exclusion principle is not violated for electrons of the similar
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WKXVIRUPDQHQHUJ\EDQGDVVKRZQLQ¿JXUH  
 x Principal quantum number n ZKLFKLQGLFDWHVWKHVL]HRI
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 x n 1, 2, 3, …l 0( s ); 2(d ), 3( f )..., (n  1). Forbidden Bands
 x Azimuthal or Angular momentum quantum number l)
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 x ml 0,1, r 2,… r l ; ms  ¨ ¸
©2¹ band.

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 x 7KH ZLGWK RI HQHUJ\ EDQGV LV JUHDWHU LI LQWHUDWRPLF GLV- The result indicates that there is at least one series of values of
tance is less depending on the crystal lattice structure. K corresponding to integer nIRUZKLFKHOHFWURQVDUHGLIIUDFWHG
 x 7KHHQHUJ\EDQGVWUXFWXUHRIVROLGVSURYLGHVDEDVLVZKLFK and do not pass freely through the crystal. This statement should
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Gallium Arsenide Versus Silicon

Fig. 1.1  x Gallium Arsenide and other compound semiconductors
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number of valence electrons per atom compared to silicon.
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electrons across the crystal lattice undergo diffraction effects in D PDWHULDO VFLHQWLVW DQG D GHYLFH GHVLJQHU ,QVSLWH RI WKLV
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positive ions of crystal atoms and valence-core electron cloud re- compound semiconductor technology till date.
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