CBSE Questions for Class 12 Engineering Physics Semiconductor Electronics: Materials,Devices And Simple Circuits Quiz 13 - MCQExams.com

The output of the given combination of gates is equivalent to:
1611943_85fe917ee5b74bb7892d50587e7b711a.png
  • NAND
  • OR
  • AND
  • NOR
In the given circuit, diode $$D$$ is ideal. The potential difference across $$4\Omega$$ resistance is:
1704675_b0ffbd494c6b4001a5a11728a9d9e36c.png
  • $$10\ V$$
  • $$5\ V$$
  • $$4\ V$$
  • $$none\ of\ these$$
At equilibrium, in a p-n junction diode the net current is
  • due to diffusion of majority charge carriers.
  • due to drift of minority charge carriers
  • zero as diffusion and drift currents are equal and opposite.
  • zero as no charge carriers cross the junction.
The impurity added in germanium crystal to make $$n-$$ type semi-conductor is:
  • aluminium
  • gallium
  • iridium
  • phosphorus
The term 'Pentium' is related to what?
  • Mouse
  • Hard Disk
  • Microprocessor
  • DVD
In the given diagram, assume that diode is not ideal. The drift current for diode is $$40\mu A$$. The potential difference across the $$4\Omega$$ resistance is:
1704682_6fed59a38924467983fc8c36bced9755.png
  • $$10\ V$$
  • $$40\times 10^{-6}V$$
  • $$160\times 10^{-6}\ V$$
  • $$none\ of\ these$$
In an insulator, band gap of the order of?
  • $$0.1eV$$
  • $$1eV$$
  • $$5eV$$
  • $$100eV$$
  • $$1MeV$$
The logic circuit in the figure represents characteristics of which logic gate?
1646213_9498ca459a0b4a4fb546f5b6da67d84f.png
  • NOR
  • OR
  • NAND
  • NOT
The energy gap between conduction band and valence band is of the order of $$0.07\ eV$$. It is a:
  • insulator
  • conductor
  • semiconductor
  • alloy
What is the plate current in a diode valve under the space charge limited operation, when the plate potential is $$60\ V$$? In a diode valve, the plate current is $$320\ mA$$, when the plate potential is $$240$$ volts:
  • $$30\ mA$$
  • $$20\ mA$$
  • $$40\ mA$$
  • $$10\ mA$$
The saturation current in a triode valve can be changed by changing 
  • the grid voltage
  • the plate voltage
  • the separation between the grid and the cathode
  • the temperature of the cathode.
A triode is operated in the linear region of its characteristics. If the plate voltage is slightly increased, the dynamic plate resistance will 
  • increase
  • decrease
  • remain almost the same
  • become zero.
The plate current in a triode valve is maximum when the potential of the grid is
  • positive
  • zero
  • negative
  • nonpositive
Choose the correct option for the forward biased characteristics of a $$p-n$$ junction:
What is the work function of tungsten at $$1500\ K$$ temperature, when a diode valve with a tungsten filament works at $$1500\ K$$? Assume the work function of tungsten at $$0\ K$$ is $$4.52\ eV$$:
  • $$4.71\ eV$$
  • $$0.39\ eV$$
  • $$8.86\ eV$$
  • $$1.25\ eV$$
In a $$p-n$$ junction diode, holes diffuse from the $$p-$$ region to the $$n-$$ region because:
  • the free electrons in the $$n-$$ region attract them
  • the are swept across the junction by the potential difference
  • there is greater concentration of holes in the $$p-$$ region as compared to $$n-$$ region
  • none of the above
In case of $$p-n$$ junction diode at high value of reverse bias, current rises sharply. The value of reverse bias is called:
  • cut off voltage
  • inverse voltage
  • zener voltage
  • critical voltage
Because of the space charge in a diode valve, 
  • the plate current decreases
  • the plate voltage increases
  • the rate of emission of thermions increases
  • the saturation current increases.
When the diode shows saturated current, dynamic plate resistance is
  • zero
  • infinity
  • indeterminate
  • different for different diodes.
A semiconducting 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
  • an intrinsic semiconductor
  • a p-type semiconductor
  • an n-type semiconductor
  • a p-n junction.
An AND gate can be prepared by repetitive use of 
  • NOT gate
  • OR gate
  • NAND gate
  • NOR gate
A hole diffuses from the p-side to the n-side in a p-n junction. This means that.
  • a bond is broken on the n-side and the electron freed from the bond jumps to the conduction band
  • a conduction electron on the p-side jumps to a broken bond to complete it
  • a bond is broken on the n-side and the electron freed from the bond jumps to a broken bond on the p-side to complete it
  • a bond is broken on the nide and the electron freed from the bond jumps to a broken bond on the n-side to complete it.
The diffusion current in a p-n junction is.
  • from the n-side to the p-side
  • from the p-side to the n-side
  • from the n-side to the p-side if the junction is forward-biased and in the opposite direction if it is reverse-biased
  • from the p-side to the n-side if the junction is forward-biased and in the opposite direction if it is reverse-biased.
Diffusion current in a p-n junction is greater than the drift current in magnitude.
  • if the junction is forward-biased
  • if the junction is reverse-biased
  • if the junction is unbiased
  • in no case
If the two ends of a p-n junction are joined by a wire,
  • there will not be a steady current in the circuit
  • there will be a steady current from the n-side to the p-side
  • there will a steady current from the p-side to the n-side
  • there may or may not be a current depending upon the resistance of the connecting wire
The drift current in a p-n junction is
  • from the n-side to the p-side
  • from the p-side to the n-side
  • from the n-side to the p-side if the junction is forward-biased and in the opposite direction if it is reverse-biased
  • from the p-side to the n-side if the junction is forward-biased and in the opposite direction if it is reverse-biased
In a p-n junction with open ends,
  • there is no systematic motion of charge carriers
  • holes and conduction electrons systematically go from the p-side to the n-side and from the n-side to the p-side respectively
  • doping donor impurities
  • irradiating ultraviolet light on it.
The $$PN$$ junction diode is used as 
  • An amplifier
  • A rectifier
  • An oscillator
  • A modulator
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?
  • Electron will move towards the positively charged plate through electron holes.
  • Holes will appear to be moving towards the negatively charged plate.
  • Both electrons and holes appear to move towards the positively charged plate.
  • Movement of electrons is not related to the movement of holes.
The valence of an impurity added to germanium crystal in order to convert it into a $$P-$$ type semi conductor is
  • $$6$$
  • $$5$$
  • $$4$$
  • $$3$$
What happens during regulation action of Zener diode?
  • The current in and voltage across the Zener remains fixed
  • The current through the series Resistance ($${R}_{s}$$) changes
  • The Zener resistance is constant
  • The resistance offered by the Zener diode changes
Truth table for the given circuit (figure) is
1798010_f7a39fcd47c14ecea6abfdf79d1d8015.png
In case of $$NPN$$ transistors the collector current is always less than the emitter current because
  • Collector side is reverse biased and emitter side is forward biased
  • After electron are lost in the base and only remaining ones reach the collector
  • Collector side is forward biased and emitter side is reverse biased
  • Collector being reverse biased attracts less electrons
Bonding in a germanium crystal (semi-conductor) is
  • Metallic
  • Ionic
  • Vander Waal's type
  • Covalent
When the electrical conductivity of a semi-conductor is due to the breaking of its covalent bonds, then the semiconductor is said to be
  • Donar
  • Aceptor
  • Intrinsic
  • Exterinsic
The laptop PC's modern electronic watches and calculator use the following for display
  • Single crystal
  • Poly crystal
  • Liquid crystal
  • Semiconductors
Silicon is a semiconductor. If a small amount of As is added to it then its electrical conductivity
  • Decreases
  • Increases
  • Remains unchanged
  • Becomes zero
Electrical conductivity of a semiconductor
  • Decrease with the rise in its temperature
  • Increase with the rise in its temperature
  • Does not change with the rise in its temeprature
  • First increases and then decreases with the rise in its temperature
In good conductors of electricity, the type of bonding that exists is
  • Ionic
  • Vander Waals
  • Covalent
  • Metallic
Two $$PN-$$ junctions can be connected in series by three different methods as shown in the figure. If the potential difference in the junctions is the same, then the correct connections will be 
  • In the circuit (1) and (2)
  • In the circuit (2) and (3)
  • In the circuit (1) and (3)
  • Only in the circuit (1)
A $$PN$$- junction has a thickness of order of 
  • $$1\ cm$$
  • $$1\ mm$$
  • $$10^{-6}\ m$$
  • $$10^{-12}\ cm$$
The intrinsic semiconductor becomes an insulator at
  • $$0^{o}C$$
  • $$-100^{o}C$$
  • $$300\ K$$
  • $$0\ K$$
A hole in a $$P-$$ type semiconductor is
  • An excess electron
  • A missing electron
  • A missing atom
  • A donor level
Given below are symbols for some logic gates
The $$XOR$$ gate and $$NOR$$ gate respectively are
1820777_53ec4421e50f40a3b80201ad9c86f916.png
  • $$1$$ and $$2$$
  • $$2$$ and $$3$$
  • $$3$$ and $$4$$
  • $$1$$ and $$4$$
Given below are four logic fate symbol (figure). Those for $$OR, NOR$$ and $$NAND$$ are respectively
1820784_5bdf033af05f4c8795c5b44b4a649f8a.png
  • $$1,4,3$$
  • $$4,1,2$$
  • $$1,3,4$$
  • $$4,2,1$$
Holes are charge carriers in 
  • Intrinsic semiconductors
  • Ionic solids
  • $$P-$$ type semiconductor
  • Metals
A crystal diode is a 
  • Non-linear device
  • Amplifying device
  • Linear device
  • fluctuating device
Zener breakdown in a semi-conductor diode occurs when 
  • Forward current exceeds certain value
  • Reverse bias exceeds certain value
  • Forward bias exceeds certain value
  • Potential barrier is reduced to zero
When the $$P$$ end of $$P-N$$ junction is connected to the negative terminal of battery and the $$N$$ end to the positive terminals of the battery, then the $$P-N$$ junction behaves like 
  • A conductor
  • An insulator
  • A super-conductor
  • A semi-conductor
Which is the correct diagram of a half-wave rectifier 
0:0:1


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