If a small amount of antimony is added to germanium crystal
1. it becomes a p–type semiconductor
2.the antimony becomes an acceptor atom
3. there will be more free electrons than holes in the semiconductor
4. its resistance is increased
Posted Date:-2022-03-10 12:40:48
Impurities like boron, aluminum, gallium or indium are added to intrinsic semiconductor to form
1.N-type doped semiconductor
2.P-type doped semiconductor
3.A junction diode
4.All of these are risks involved in development.
Posted Date:-2022-03-10 13:01:10
A p-type semiconductor has an acceptor density of 1020 atoms/m3 and intrinsic concentration of 2.5×1019 m-1 at 300K. The electron concentration in this p-type semiconductor is
1. 6.23 × 10 18
2.6.25 × 10 19
3. 62.5 × 10 19
4. 62.5 × 10 18
Posted Date:-2022-03-10 13:59:58
A semiconductor device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops to almost zero. The device may be a/an
1.intrinsic semiconductor
2.p-type semiconductor
3.n-type semiconductor
4.p-n junction diode
Posted Date:-2022-03-10 12:43:07
A strip of copper and another of germanium are cooled from room temperature to 80K. The resistance of
1.each of these decreases
2.copper strip increases and that of germanium decreases
3. copper strip decreases and that of germanium increases
4.each of these increases
Posted Date:-2022-03-10 12:42:08
An electron in conduction band
1. Is located near the top of the crystal
2.Is bound to its parent atom
3. Has no charge
4.Has a higher energy than an electron in the valence band
Posted Date:-2022-03-10 13:58:33
At room temperature a semiconductor material is
1.. Perfect insulator
2.Conductor
3.Slightly conducting
4.Any one of the above.
Posted Date:-2022-03-10 12:58:18
At zero K (or at absolute zero) the conduction band may be partially filled in
1. Conductors only
2. Insulators only
3.Semiconductors only
4.Conductors and semiconductors
Posted Date:-2022-03-10 13:58:56
Barrier potential of a P-N junction diode does not depend on
1. doping density
2.diode design
3. temperature
4.forward bias
Posted Date:-2022-03-10 12:49:46
Bridge type rectifier uses
1.four diodes
2.six diodes
3.two diodes
4.one diode
Posted Date:-2022-03-10 12:53:57
By increasing the temperature, the specific resistance of a conductor and a semiconductor
1. increases for both
2. decreases for both
3. increases, decreases
4.decreases, increases
Posted Date:-2022-03-10 12:41:21
Carbon, Silicon and Germanium atoms have four valence electrons each. Their valence and conduction bands are separated by energy band gaps represented by (Eg)C, (Eg)Si and (Eg)Ge respectively. Which one of the following relationship is true in their case?
1.(Eg)C > (Eg)Si
2.(Eg)C < (Eg)Si
3.(Eg)C = (Eg)Si
4.(Eg)C < (Eg)Ge
Posted Date:-2022-03-10 12:42:36
Conductivity of the metal is
1. 4.382 × 10 5 S/m
2. 43.82 × 10 5 S/m
3.438.2 × 10 5 S/m
4..4382 × 10 5 S/m
Posted Date:-2022-03-10 13:54:17
Current density for the field applied in question 4 would be
1.3.15 × 10 10 A / m 3
2.3.15 × 10 11 A / m 3
3. .315 × 10 10 A / m 3
4.3.15 × 10 10 A / m 3
Posted Date:-2022-03-10 13:55:29
Diffusion current in a p-n junction is greater than the drift current in magnitude
1.if the junction is forward-biased
2. if the junction is reverse-biased
3.if the junction is unbiased
4. in no case
Posted Date:-2022-03-10 12:44:40
Filter circuit
1.eliminates a.c. component
2.eliminates d.c. component
3.does not eliminate a.c. component
4.None of these
Posted Date:-2022-03-10 12:47:57
For a junction diode the ratio of forward current (If) and reverse current (Ir) is [e = electronic charge, V = voltage applied across junction, k = Boltzmann constant, T = temperature in kelvin]
1.e–V/kT
2.eV/kT
3.(e–eV/kT + 1)
4.(eeV/kT – 1)
Posted Date:-2022-03-10 12:48:29
For silicon, the energy gap at 300 K is
1. 1.1 W
2.1.1 J
3. 1.1 eV
4.None of these
Posted Date:-2022-03-10 12:58:59
Forward biasing is that in which applied voltage
1.increases potential barrier
2. cancels the potential barrier
3.is equal to 1.5 volt
4.None of these
Posted Date:-2022-03-10 12:45:01
Good conductors does not have hole current because they are
1.Full of electrons
2.Have large forbidden energy gap
3. Have no valence band
4.Have overlapping valence band and conduction band
Posted Date:-2022-03-10 13:59:31
If the two ends of a p-n junction are joined by a wire
1.there will not be a steady current in the circuit
2.there will be a steady current from the n-side to the p side
3.there will be a steady current from the p-side to the n side
4.there may or may not be a current depending upon the resistance of the connecting wire
Posted Date:-2022-03-10 12:43:29
In a half wave rectifier, the r.m.s. value of the a.c. component of the wave is
1. equal to d.c. value
2. more than d.c. value
3.less than d.c. value
4.Zero
Posted Date:-2022-03-10 12:55:11
In a metal
1.The electrical conduction is by electrons and holes
2.The conductivity decreases with the rise in temperature
3.The conduction band is empty
4.. None of the above
Posted Date:-2022-03-10 13:04:03
In a N-type semiconductor, the position of Fermi-level
1.Is lower than the center of energy gap
2. Is at the center of energy gap
3.Is higher than the center of energy gap
4. Can be any where
Posted Date:-2022-03-10 13:01:35
In a P -N junction
1.the potential of P & N sides becomes higher alternately
2.the P side is at higher electrical potential than N side.
3. the N side is at higher electric potential than P side.
4.both P & N sides are at same potential.
Posted Date:-2022-03-10 12:49:20
In a P type material the Fermi level is 0.3 eV above the valence band. The concentration of accepter atoms is increased. The new position of Fermi level is likely to be
1.0.5 eV above the valence band.
2.0.2 eV above the valence band.
3.Below the valence band.
4.None of the above.
Posted Date:-2022-03-10 12:57:20
In a semiconductor diode, the barrier potential offers opposition to
1.holes in P-region only
2.free electrons in N-region only
3.majority carriers in both regions
4.majority as well as minority carriers in both regions
Posted Date:-2022-03-10 12:48:55
In an intrinsic semiconductor, the Fermi level
1.Lies at the center of forbidden energy gap.
2.Is near the conduction band.
3.Is near the valence band.
4.May be anywhere in the forbidden energy gap.
Posted Date:-2022-03-10 12:56:03
In forward biasing of the p–n junction
1.the positive terminal of the battery is connected to p–side and the depletion region becomes thick
2. the positive terminal of the battery is connected to n–side and the depletion region becomes thin
3.the positive terminal of the battery is connected to n–side and the depletion region becomes thick
4.the positive terminal of the battery is connected to p–side and the depletion region becomes thin
Posted Date:-2022-03-10 12:50:32
In reverse biasing
1.large amount of current flows
2. potential barrier across junction increases
3.depletion layer resistance increases
4.no current flows
Posted Date:-2022-03-10 12:47:23
In the middle of the depletion layer of a reverse- biased p-n junction, the
1. electric field is zero
2.potential is maximum
3.electric field is maximum
4. potential is zero
Posted Date:-2022-03-10 12:53:34
In V-I characteristic of a p-n junction, reverse biasing results in
1.leakage current
2. the current barrier across junction increases
3. no flow of current
4.Large current flow
Posted Date:-2022-03-10 12:46:55
Most commonly used semiconductor material is
1.Silicon
2.Germanium
3.Mixture of silicon and germanium
4.None of the above.
Posted Date:-2022-03-10 12:57:50
Reverse bias applied to a junction diode
1. increases the minority carrier current
2. lowers the potential barrier
3.raises the potential barrier
4.increases the majority carrier current
Posted Date:-2022-03-10 12:50:07
The average value of output direct current in a full wave rectifier is
1.I<sub>0</sub>/Ï€
2. I<sub>0</sub>/2
3.Ï€ I<sub>0</sub>/2
4.2 I<sub>0</sub>/Ï€
Posted Date:-2022-03-10 12:54:48
The average value of output direct current in a half wave rectifier is
1. I<sub>0</sub>/Ï€
2.I<sub>0</sub>/2
3. π I<sub>0</sub>/2
4.2 I<sub>0</sub>/Ï€
Posted Date:-2022-03-10 12:54:20
The cause of the potential barrier in a p-n junction diode is
1.depletion of positive charges near the junction
2. concentration of positive charges near the junction
3. depletion of negative charges near the junction
4.concentration of positive and negative charges near the junction
Posted Date:-2022-03-10 12:52:35
The diffusion current in a p-n junction is from the
1. n-side to the p-side
2.p-side to the n-side
3.n-side to the p-side if the junction is forward-biased and in the opposite direction if it is reverse-biased
4. p-side to the n-side if the junction is forward-biased and in the opposite direction if it is reverse-biased
Posted Date:-2022-03-10 12:44:17
The drift current in a p-n junction is from the
1.n-side to the p-side
2. p-side to the n-side
3.n-side to the p-side if the junction is forward-biased and in the opposite direction if it is reverse biased
4.p-side to the n-side if the junction is forward-biased and in the opposite direction if it is reverse-biased
Posted Date:-2022-03-10 12:43:54
The energy gap in a semiconductor
1.Increases with temperature
2.Does not change with temperature
3.Decreases with temperature
4.Is zero
Posted Date:-2022-03-10 13:04:38
The forbidden energy gap Eg in case of semiconductors is of the order of
1. 6 eV
2. 1 eV
3. 0.1 eV
4.None of the mentioned
Posted Date:-2022-03-10 13:53:46
The forbidden gap for germanium is
1. 0.12 eV
2.0.72 eV
3.7.2 eV
4.None of These
Posted Date:-2022-03-10 12:59:43
The mobility of electrons in a material is expressed in unit of:
1.V/s
2.m2 /V-s
3.m 2 /s
4. J/K
Posted Date:-2022-03-10 13:02:11
The pentavalent impurities like antimony, arsenic, bismuth and phosphorus, added to intrinsic semiconductors are called
1.Acceptor or P-type impurities
2.Donor or P-type impurities
3.Acceptor or N-type impurities
4.Donor or N-type impurities
Posted Date:-2022-03-10 13:00:36
The process of adding impurities to a pure semiconductor is called
1.Mixing
2.Doping
3. Diffusing
4. None of the above
Posted Date:-2022-03-10 13:00:07
The ratio of forward biased to reverse biased resistance for p-n junction diode is
1.10–1 : 1
2.10–2 : 1
3.104 : 1
4. 10–4 : 1
Posted Date:-2022-03-10 12:53:03
The ratio of impurity atoms to intrinsic semiconductor atoms in an extrinsic semiconductor is about.
1.1:10
2.1:103
3.1:105
4.1:10
Posted Date:-2022-03-10 12:56:48
Two initially identical samples A and B of pure germanium are doped with donors to concentrations of 1x1020 and 3x1020respectively. If the hole concentration in A is 9x1012, then the hole concentration in B at the same temperature will be
1.3x1012 m-3
2.7x1012 m-3
3.11x1012 m-3
4.27x1012 m-3
Posted Date:-2022-03-10 13:05:20
When p-n junction diode is forward biased then
1.both the depletion region and barrier height are reduced
2.the depletion region is widened and barrier height is reduced
3.the depletion region is reduced and barrier height is increased
4.Both the depletion region and barrier height are increased
Posted Date:-2022-03-10 12:50:56
Which one of the following statement(s) is true?
1.Resistivity of conductors increases with increase in temperature.
2.Resistivity of semiconductors increases with increase in temperature
3.Resistivity of semiconductors decreases with increase n temperature.
4.Resistivity of insulators decreases with decrease in temperature
Posted Date:-2022-03-10 13:49:23