2. Major part of electric current in an intrinsic semiconductor is due to drift of
(a) conduction-band electrons
(b) valence-band electrons
(c) conduction-band holes
(d) valence-band holes
(e) None of the above.
3. The rms value of current in a full-wave rectifier is given as
(a) [tex]$I_m / \pi$[/tex]
(b) [tex]$I_m / 2$[/tex]
(c) [tex]$I_m / \sqrt{ } 2$[/tex]
(d) [tex]$2 l_m / \pi$[/tex]
Answer (1)
( a ) ; ( c )
Explanation
Question 2 Analysis In an intrinsic semiconductor, the number of electrons in the conduction band is equal to the number of holes in the valence band. Both electrons and holes contribute to the electric current. However, electrons in the conduction band have higher mobility than holes in the valence band. Therefore, the major part of the electric current is due to the drift of conduction-band electrons.
Question 3 Analysis The root mean square (RMS) value of current in a full-wave rectifier is given by: I r m s = 2 I m where I m is the peak current.
Final Answer Therefore, the correct answer to question 2 is (a) conduction-band electrons, and the correct answer to question 3 is (c) I m / 2 .
Examples
Semiconductors are used in almost every electronic device. Understanding how current flows in semiconductors is crucial for designing and improving these devices. For example, knowing that conduction-band electrons are the primary current carriers in intrinsic semiconductors helps engineers optimize transistor designs for better performance. Similarly, understanding the RMS current in a full-wave rectifier is essential for designing power supplies that efficiently convert AC to DC, which is used in many electronic devices.
