Explanation
We cannot measure the potential barrier of a PN-junction by connecting a sensitive voltmeter across its terminals because in the depletion region, there are no free electrons and holes and in the absence of forward biasing. PN-junction offers infinite resistance.
The energy gap between valence band and conduction band in germanium is 0.76 eV and the energy gap between valence band and conduction band in silicon is 1.1 eV. Also, it is true that thermal energy produces fewer minority carriers in silicon than in germanium.
Two PN-junctions placed hack to back cannot work as NPN transistor because in transistor the width and concentration of doping of P-semiconductor is less as compared to width doping of N-type semiconductor type.
Common emitter is preferred over common base because all the current, voltage and power gain of common emitter amplifier is much more than the gains of common base amplifier.
In PN-junction, the diffusion of majority carriers takes place when junction is forward biased and drifting of minority carriers takes place across the function, when reverse biased. The reverse bias opposes the majority, carriers but makes the minority carriers to cross the PN-junction. Thus the small current in µA flows during reverse bias.
These gates are called digital building blocks because using these gates only (either NAND or NOR) we can compile all other gates also (like OR , AND, NOT, XOR).
Potential difference across the resistance is zero, because diode is in reverse biasing hence no current flows.
When the reverse voltage across the zener diode is equal to or more than the breakdown voltage, the reverse current increases sharply.
In vacuum tubes. vacuum is necessary and the working of semiconductor devices is independent of heating or vacuum.
(1 = high, 0 = low)
Input to A is in the sequence, 1, 0, 1, 0.
Input to B is in the sequence, 1, 0, 0, 1.
Sequence is inverted by NOT gate
Thus inputs to OR gate becomes 0, 1, 0, 1 and 0, 1, 1,0
output of OR gate becomes 0, 1, 1, 1.
Since for OR gate 0 + 1 = 1. Hence choice (a) is correct.
Number of holes in base region increases hence recombination of electron and hole are also increases in this region. As result base current increases which in turn decreases the collector current.
In sodium chloride the Na+ and Cl- ions both have noble gas electron configuration corresponding to completely filled bands. Since the bands do not overlap, there must be a gap between the filled bands and the empty bands above them, so NaCl is an insulator.
Pure Cu is already an excellent conductor, since it has a partially filled conduction band, furthermore, Cu forms a metallic crystal as opposed to the covalent crystals of silicon or germanium, so the scheme of using an impurity to donatc or accept an electron does not work for copper. In fact adding impurities to copper decreases the conductivity because an impurity tends to scatter electrons, impeding the flow of current.
Charge carriers inside the P-type semiconductor are holes (mainly). Inside the conductor charge carriers are electrons and for cell ions are the charge carriers.
Ionic bonds come into being when atoms that have low ionization energies, and hence lose electrons rapidly, interact with other atoms to acquire excess electrons. The former atoms give up electrons to the latter and they there upon become positive and negative ions respectively.
The net force on electron placed at the centre of bcc structure is zero.
(By the principle of superposition of coulomb forces)
Absence of one electron creates the positive charge of magnitude equal to that of electronic charge.
Impurity increases the conductivity
Aluminium is trivalent impurity
In insulators, the forbidden energy gap is very large, in case of semiconductor it is moderate and in conductors the energy gap is zero.
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