Identify the operation performed by the circuit given below:
In the circuit of figure, treat the diodes as ideal. Current in the 4-ohm resistor is (In A)
In the shown common emitter amplifier circuit, β = 80 , V B E = 0.7 volt . The value of R C is k Ω [Given V C E = 3 V ]
A n-p-n transistor operates in a common emitter mode as shown below. Given that I c = 4 mA , V CE = 4 V , V BE = 0.6 V . Then R L is
The reading of ammeter in the following circuit. (Assuming forward voltage drop across diode is zero)
Which of the following statements is not true?
In an NPN transistor, 10 10 electrons enter the emitter in 10 − 6 sec. If 2% electrons are lost in the base, calculate the current transfer ratio.
The correct relation between n e a n d n h in an intrinsic semiconductor at ordinary temperature is
An n-type and p-type silicon semiconductor can be obtained by doping pure silicon with
Three photodiodes D 1 , D 2 a n d D 3 are made of semiconductors having band gaps of 2.5 eV, 2 eV and 3 eV respectively. Which one will be able to detect of wavelength of 6000 A o
The percentage of efficiency for full wave rectifier
In case of common-emitter configuration of transistor current gain is more than one, because
What is the value of A . A ¯ in Boolean algebra
Zener diode used as voltage regulator in which bias
If the ratio of the concentration of electron to that of holes in a semiconductor is 7 5 and the ratio of currents is 7 4 , then what is the ratio of their drift velocities
A Ge specimen is doped with Al. The concentration of acceptor atom is 10 21 a t o m s / m 3 . Given that the intrinsic concentration of electron hole pairs is 10 19 / m 3 , the concentration of electrons in the specimen is
The value of A + A ¯ in the Boolean algebra is
What is the current in the circuit shown below
The electrical conductivity of a semiconductor increases when electromagnetic radiation of wavelength shorter than 2480 nm is incident on it. The band gap in eV.
The peak voltage in the output of a halfwave diode rectifier fed with a sinusoidal signal without filter is 20V. The dc component of the output voltage is
Current in the circuit will be
A p-n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV. It can detect a signal of wavelength
Ga As (with a band gap=1.5eV) as an LED can emit
In the given circuit, the current through the battery is
In a transistor, a change of 5mA in the emitter current produces a change of 4.95mA in the collector current. The base current changes by
If the voltage between the terminals A and B is 17 V and Zener breakdown voltage is 9V, then the potential across R is
The voltage gain of an amplifier with 9% negative feedback is 10. The voltage gain without feedback will be
To get an output 1 from the circuit shown in figure. The inputs must be
A common emitter transistor amplifier has a current gain of 20. If the load resistance is 4 k Ω and input resistance is 500 Ω , the voltage gain of the amplifier is
A cell of emf 4.5 V is connected to a junction diode whose barrier potential is 0.7 V. If the external resistance in the circuit is 190Ω, then the current in the circuit in Ampere
The length of germanium rod is 1 cm and its area of cross-section is 1 m m 2 . If for germanium n i = 2.5 × 10 19 m − 3 , μ e = 0.39 m 2 v − 1 s − 1 , μ h = 0.19 m 2 v − 1 s − 1 . Its resistance in ohms is
In the given Boolean expression, y = A . B ¯ + B . A ¯ , if A=1, B=1 then y will be
The peak voltage in the output of a half wave diode rectifier fed with a sinusoidal signal without filter is 5 V. The dc component of the output voltage is
In a reverse biased diode, when the applied voltage changes by 2V, the current is found to change by 0.25μA. The reverse bias resistance of the diode is
A p-n photo diode is fabricated from a semiconductor with a bandgap of 5eV. It can detect a signal of wavelength
A N-type silicon sample of width 2 × 10 − 3 m , thickness and length 3 × 10 − 2 m carries a current of 2.4mA, when the voltage is applied across the length of the sample. The free electron density is 10 22 m – 3 . Select which one of them is incorrect
In a transistor, a change of 5mA in the emitter current produces a change of 4.95mA in the collector current. The base current changes by
If the voltage between the terminals A and B is 15V and zener breakdown voltage is 8V, then the potential across R is
In a transistor circuit shown here the base current is 25µA. The value of the resistor R b is
A Zener diode, having breakdown voltage equal to 10 V, is used in voltage regulator circuit shown in figure. The current through the diode is
The resonance frequency of the tank circuit of an oscillator when L = 2 π 2 m H and C = 0.8 μ F are connected in parallel is
To get an output o from the circuit shown in figure. The inputs must be
A common emitter transfer amplifier has a current gain of 25. If the load resistance is 3kΩ and input resistance is 750Ω, the voltage gain of the amplifier is
In the given circuit the current flow through the p-n junction diode is in Ampere
Current in the circuit will be
Find V A B
Calculate β of a transistor, if the current gain α = 0.98
Boolean relation at the output stage-Y for the following circuit is:
In the given circuit, value of Y is :
The current i in the network is:
Consider the given circuit, Point C maintained at +5V and point D is earthed. If the following input is given at point A.
In a p-n junction without any external voltage
A block of pure Si at 300 K has a length of 10 cm and an area of cross-section 1 cm 2 . A battery of emf 2V is connected across it. The mobility of electrons is 0.14 m 2 V –1 s –1 and their number density is 1.5×10 16 m –3 . The electron current is:-
The current through an ideal PN-junction shown in the following circuit diagram will be
This symbol represents
Which gates is represented by this figure
In a n-p-n transistor, 10 10 electrons enter the emitter in 10 -6 s and 4% of the electrons are lost in base. The current transfer ratio will be
The transfer ratio of the transistor is 50. The input resistance of the transistor when used in the CE configuration is 1 k Ω . The peak value for an AC input voltage of 0.01 V of collector current is
In the figure, potential difference (in V) between A and B is
The current (in A) in the network is
The combination of NAND gates shown here under are equivalent to
In the given circuit, V 1 and V 2 are
In the following circuit, three P-N junction diodes D 1 , D 2 and D 3 are ideal for the following potential of A and B. The correct increasing order of resistance between A and B will be Sno. A B (i) -10V -5V (ii) -5V -10V (iii) -4V -12V
Calculate the conductivity of silicon crystal at 300 K. It is given that μ e = 1350 c m 2 / V s , μ n = 480 c m 2 / V s and at 300 K, the electron hole pair concentration is 1.072 × 10 10 p e r c m 3
Find the output voltage in the given transistor circuit. ( β = 100 )
In the circuit given below, V(t) is the sinusoidal voltage source. Voltage drop V A B ( t ) across the resistance ‘R’ is
A potential barrier of 0.5V exists across a p-n junction. An electron with speed 5 × 10 6 m / s approaches the p-n junction from the n-side, with what speed will it enter the p-side?
The transfer ratio β of transistor is 50. The input resistance of a transistor when used in CE configuration is 1 k Ω . The peak value of the collector A.C current for an A.C input voltage of 0.01V peak is
Which is the correct diagram of half wave rectifier.
Which of the following gates will have an output of 1.
A silicon transistor amplifier circuit is given below. ( β = 100 ) . Find collector – emitter voltage
A diode used in the circuit shown in figure has a constant voltage drop of 0.5 V at all currents and a maximum power rating of 100 mW . What should be the value of resistance ‘R’ connected in series with diode for obtaining maximum current ?
For a transistor β = 45 and voltage drop across 1 k Ω which is connected in the collector circuit is 1 volt. Find the base current for CE connection
In the given transistor circuit, the base current is 35 μ A , the value of R b is
Find the potential difference between A & B in the given circuit.
In the network shown in figure, find V 0 .
The saturation current density of a P-N junction germanium diode is 250 m A / m 2 at 300 K. Find the voltage ( in V ) that would have to be applied across the junction to cause a forward current density 10 5 A / m 2 to flow. ( K = 1.38 × 10 − 23 J / K )
The Boolean equation for the circuit given in figure is
An LED is constructed from a p-n junction based on a certain Ga-As-P semiconducting material whose energy gap is 1.9 eV. What is the wavelength of the emitted light in nm?
A transistor is connected in CE configuration. The collector supply in 8V and the voltage drop across a resistor of 800 Ω in the collector circuit is 0.5 V. If α = 0.96 , then the base current is x μ A . Find x
A pnp transistor is used in CE mode in an amplifier circuit. A change of 40 μ A in the base current brings a change of 2 mA in collector current and 0.04 V in base emitter voltage. The input resistance ( R i n ) in k Ω is
Copper, a mono valent, has molar mass 63.54 g m / m o l e and density 8.96 g m / c m 3 , the number density of conduction electrons in copper is n × 10 28 / m 3 . Find ‘n’
In figure, what is the voltage needed at the source, to maintain 15 V across the load resistance R L , assuming that the series resistance R is 200 Ω and Zener requires a maximum current of 10mA to work satisfactory?
An A.C supply of 230 V is applied to a half wave rectifier circuit through a transformer of turn ratio 10 : 1. Find the output D.C voltage (approximately)
The forbidden energy band gap in conductors, semiconductors and insulators are E G 1 , E G 2 a n d E G 3 respectively. The relation among them is
The fermi level of an intrinsic semiconductor is pinned at the center of the band gap. The probability of occupation of the highest electron state in valance band at room temperature, will be
In p-type semiconductors, conduction is due to
The value of current in the following diagram will be
The reverse bias in a junction diode is changed from 8 V to 13 V, then the value of the current changes from 40μA to 60μA. The resistance of junction diode will be
A 220 V A.C supply is connected between points A and B. What will be Potential Difference V across the capacitor
For a junction diode, the ratio of forward current ( I f ) and reverse current ( I r ) is
In the half wave rectifier, circuit operating from 50Hz mains frequency, the fundamental frequency in the ripple should be
Number of diodes used in the half wave rectifier
Three amplifier stages each with a gain of 10 are cascaded. The overall gain is
A truth table is given below. Which of the following has this type of truth table.
The correct relation between the two current gains α and β in a transistor is
In germanium crystal, the forbidden energy gap between the valance band and conduction band in eV
Which gate is represented by the symbolic diagram given here
In CB configuration current gain 0.98, the current gain in CE configuration
A n-type silicon sample of width 4 x 10 – 3 m , thickness and length 6 × 10 – 2 m carriers a current of 4.8 mA, when the voltage is applied across the length of the sample. The free electron density is 10 22 m – 3
F i n d V A B
In a reverse biased diode, when the applied voltage changes by 1V, the current is found to change by 0.5μA. The reverse bias resistance of the diode is
A light emitting diode has a voltage drop of 2 volt across it and passes a current of 10mA, when it operates with a 6 volt battery through a limiting resistor R. The value of R is
A Zener diode, having breakdown voltage equal to 15 V, is used in a voltage regulator circuit shown in figure. The current through the diode is
In NPN transistor the collector current is 8mA. If 80% of electrons emitted reach the collector, then
In a transistor circuit shown here the base current is 35μA. The value of the resistor R b is
The resonance frequency of the tank circuit of an oscillator when L = 10 π 2 m H and C = 0 . 04 μ F are connected in parallel is
In the given circuit the current flow through the p-n junction diode is ( in A)
In the given circuit, the current through the battery is
The maximum efficiency of half wave rectifier is
A light emitting diode has a voltage drop of 5 volt across it and passes a current 2mA when it operates with a 9 volt battery through a limiting resistor R. The value of R is
Ga As (with a band gap=1.5eV) as an LED can emit
In NPN transistor the collector current is 8mA. If 80% of electrons emitted reach the collector, then
The voltage gain of an amplifier with 7% negative feedback is 9. The voltage gain without feedback will be
The length of germanium rod is 2 cm and its area of cross section is 2 m m 2 . If for germanium n i = 2 . 5 x 10 19 m – 3 , μ e = 0 . 39 m 2 v – 1 s – 1 , μ h = 0 . 19 m 2 v – 1 s – 1 . Its resistance in ohms is
A cell of emf 5V is connected to a junction diode whose barrier potential is 0.3V. If the external resistance in the circuit is 200Ω, then the current in the circuit in Ampere
In the given Boolean expression y = A . B ¯ + B . A ¯ If A=1, B=0 then y will be
A Ge specimen is doped with Al. The concentration of acceptor atom is 10 20 a t o m s / m 3 . Given that the intrinsic concentration of electron hole pairs is 10 17 / m 3 , the concentration of electrons in the specimen is
What is the current in the circuit shown below
The given circuit has two ideal diodes connected as shown in the figure below. The Current flowing through the resistance R 1 will be
In the given circuit, the equivalent resistance between A & B is ( if A has negative potential and B has positive potential)
A transistor is used in common – emitter mode in an amplifier circuit. When a signal of 20 mV is added to the base – emitter voltage, the above current changes by 20 μ A and the collector current changes by 2 mA. The load resistance is 5 k Ω . Calculate a) The input resistance R B E , b) The transconductance and c) The voltage gain.
Find the current produced at room temperature in a pure germanium plate of area 2 × 10 − 4 m 2 and thickness is 1.2 × 10 − 3 m when a potential of 5 V is applied across the faces. Concentration of carriers in germanium at room temperature is 1.6 × 10 6 m − 3 . The mobilities of electrons and holes are 0.4 m 2 v − 1 s − 1 and 0.2 m 2 v − 1 s − 1 respectively . The heat generated in the plate in 100 second is
A semi conductor has an electron concentration of 0.60 × 10 11 m − 3 and a hole concentration of 6 × 10 19 m − 3 . Calculate its conductivity. Given electron mobility is 0.125 m 2 v − 1 s − 1 , hole mobility is 0.032 m 2 v − 1 s − 1
In a common emitter amplifier the load resistance of the output circuit is 792 times the resistance of the input circuit. If α = 0.99 , then voltage gain is
Truth table for the system on four NAND gates as shown in figure is
Write Boolean equation for the given the output of figure
Common emitter amplifier circuit, built using an n – p – n transistor, is shown in the figure . Its DC current gain is 250, R c = 1 k Ω and V c c = 10 V . What is the minimum base current for V C E to reach saturation.
The input signals at NAND gate is given below
From the circuit shown below, the maximum and minimum values of Zener diode current are
The energy of a photon of sodium light λ ( 589 n m ) equals the band gap of a semiconducting material. Find the minimum energy E (in eV) required to create a hole – electron pair.
The I– V characteristic of a p – n junction diode is shown in figure. Find the approximate dynamic resistance of the p – n junction when a). a forward bias of 1 Volt is applied b). a forward bias of 2 Volt is applied
The applied input AC power to a full wave rectifier is 80 W and DC output power obtained is 60 W . The rectification efficiency is χ then χ is
The current gain of a transistor in common emitter circuit is 40. The ratio of emitter current to base current is R , then R is
An n – p – n transistor is used in common emitter configuration with an amplifier with 1 k Ω load resistance. Signal voltage of 10 mV is applied across the base – emitter. This produces a 3mA change in the collector current and 15 μ A change in the base current of the amplifier. The input resistance and voltage gain are
In a common emitter amplifier the load resistance of the output circuit is 792 times the resistance of the input circuit. If α = 0.99 , then voltage gain is
The peak voltage in the output of a half wave rectifier fed with a sinusoidal signal without filter in 40V. The D.C component of the output Voltage is
The combination of gates shown below yields.
When a semi-conducting material is doped with an impurity, new acceptor levels are created. In a particular thermal collision, a valence electron receives an energy equal to 2 kT (k = Boltzmann Constant, T = Absolute Temperature) and just reaches one of the acceptor levels. Assuming that the energy of the electron was at the top edge of valence band and the temperature T is equal to 300 K . Find the energy of acceptor levels above the valence band.
In a Silicon transistor , the base current is changed by 20 μ A . This results in a change of 0.02 V in base to emitter voltage and a change of 2mA in the collector current. Find the transconductance of transistor.
Assume that the number of hole – electron pair in an intrinsic semiconductor is proportional to e △ E 2 k T . H e r e , △ E = energy . gap and k = 8.62 × 10 − 5 e V / k e l v i n . The energy gap for silicon is 1.1 eV. The ratio of electron hole pairs at 300 K and 400 K is e − x . Find x
To write the decimal number 37 in binary , no of digits are required are x then x is
For a transmitter the value of β is 100 and value of α is x × 10 − 2 then find x
The circuit shown below is working as 6 V dc regulated voltage source when 10 V dc used as input, the power dissipated (in mW) in each diode is ( Consider both zener diodes identical)
In the given circuit, the equivalent resistance between A and B (if A has positive potential and B has negative potential) is
The circuit shown in the figure contains two diodes each with a forward resistance of 50 ohm and with infinite backward resistance. If the battery voltage is 6 V the current through the 100 ohm resistance (in ampere) is
A change of 8.0mA in the emitter current brings a change of 7.9mA in the collector current . Find the value β .
Mobilities of electrons and holes in a sample of intrinsic germanium at room temperature are 0.36 m 2 / Vs and 0.17 m 2 / V s . The electron and hole densities are each equal to 2.5 × 10 19 m − 3 . Electrical conductivity of Germanium is
A semiconductor has an electron concentration of 0.45 × 10 12 m − 3 and a hole concentration of 5 × 10 20 m − 3 . Calculate its conductivity. Given electron mobility is 0.135 m 2 v − 1 s − 1 . Hole mobility is 0.048 m 2 v − 1 s − 1
A CE amplifier is designed with a transistor having α = 0.99 . Input impedance 1 k Ω and load 10 k Ω . Voltage gain will be
Which of the following truth table is true?
The Boolean expression of the output T of the inputs A and B for the circuit shown in the figure.
The following figures shows a logic gate circuit with two inputs A & B and the output C. The voltage wave forms of A, B & C are as shown below . The logic gate is
A 10 V Zener diode along with a series resistance is connected across 40 V supply. Calculate the minimum value of the resistance regulated, if the maximum Zener current is 500 mA.
A certain npn transistor has the common emitter output characteristics as shown in figure. The emitter current at V c c = 10 V and I b = 60 μ A is P × 10 − 4 A . Then the value of p is ——————-
In a full wave rectifier circuit operating from 50 Hz moving frequency, the fundamental frequency in the ripple would be (in Hz)
The band gap in germanium is Δ E = 0.68 eV . Assuming that the number of hole – electron pairs is proportional to e − Δ E 2 k T , find the percentage increase in the number of charge carriers in pure germanium as the temperature is increased from 300 K to 320 K
An npn transistor in a common emitter mode is used as a simple voltage – amplifier with a collector current of 4 mA. The terminal of 8 V battery is connected to the collector through a load resistance R L and base through load resistance R B . The collector emitter voltage V C E = 4 V , base emitter voltage V B E = 0.6 V and current amplification factor β = 100. Find R B (in ohm).
A potential barriers of 0.5 eV exists in p-n junction. If an electron approaches the p-n junction from the n – side with speed of 5 × 10 5 m / s , then electron will enter the P side with velocity (in m/s)
In a full wave rectifier circuit operating from 90 HZ mains frequency. The fundamental frequency in the ripple would be
In a transistor if I C I E = α and I C I B = β , if α varies between 20 21 and 100 101 , then the value β of lies between
For a transistor amplifier in common emitter configuration for load impedance of 1 k Ω ( h f e = 50 and h o e = 25 μ A / v ) the current gain is
The output Y of the logic circuit shown in figure is
The potential difference across the collector of a transistor, used in common emitter mode is 1.5 V , with the collector resistance 3 k Ω . Find the emitter current in mA , if gain of transistor is 50.
Let △ E denotes the energy gap between the valence band and the conduction band. The population of conduction electrons (and of the holes) is roughly proportional to e − △ E / 2 k T . Find the ratio of the concentration of conduction electrons in diamond to that in silicon at room temperature 300 K . △ E for silicon is 1.1 eV and for diamond is 6.0 eV.
The number of silicon atoms per m 3 is 5 × 10 28 . This is doped simultaneously with 5 × 10 22 atoms per m 3 of arsenic and 5 × 10 20 atoms per m 3 of Indium .Given that n i = 1 . 5 × 10 16 m − 3 . If the number of electrons is z × 10 21 m − 3 then z is
The circuit shown below is working as 10 V dc regulated voltage source. When 12 V is used as input, the power dissipated (in mW) in each diode is (Consider both Zener diodes are identical)
Which of the following gives a reversible operation?
Which of the following gives a reversible operation?
In the figure, potential difference between A and B is:
Both the diodes used in the circuit shown are assumed to be ideal and have negligible resistance when these are forward biased. Built in potential in each diode is 0.7 V. For the input voltages shown in the figure, the voltage (in Volts) at point A is –
Two identical capacitors A and B , charged to the same potential 5V are connected in two different circuits as shown below at time t=0 . If the charge on capacitors A and B at time t = C R is Q A a n d Q B respectively, then (here e is the base of natural logarithm)
The circuit shown below is working as a 8 V d c regulated voltage source. When 12 V is used as input, the power dissipated (in m W )in each diode is; ( considering both Zener diodes are identical)
In the following, digital circuit, what will be the output at ‘Z’, when the input (A, B) are (1, 0), (0, 0), (1, 1), (0, 1):
When a diode is forward biased, it has a voltage drop of 0.5 V. The safe limit of current through the diode is 10 mA. If a battery of emf 1.5 V is used in the circuit, the value of minimum resistance to be connected in series with the diode so that the current does not exceed the safe limit is :
Which of the following will NOT be observed when a multimeter (operating in resistance measuring mode) probes connected across a component, are just reversed ?
If a semiconductor photodiode can detect a photon with a maximum wavelength of 400nm, then its band gap energy is : Planck’s constant h = 6.63 × 10 − 34 J . s . Speed of light c = 3 × 10 8 m / s
Take the breakdown voltage of the Zener diode used in the given circuit as 6V. For the input voltage shown in figure below, the time variation of the output voltage is : (Graphs drawn are schematic and not to scale)
With increasing biasing voltage of a photodiode, the photocurrent magnitude:
Two Zener diodes (A and B) having breakdown voltages of 6 V and 4 V respectively, are connected as shown in the circuit below. The output voltage V 0 variation with input voltage linearly increasing with time, is given by ( V i n p u t =0V at t = 0)( figures are qualitative)
The logic symbols shown here are logically equivalent to:
In the following common emitter circuit, if β = 100 . V C E = 7 V , V B E = negligible, R C = 2 k Ω , then I B = ?
In semiconductor, the concentration of electrons and holes are 8 × 10 18 / m 3 and 5 × 10 18 / m 3 , respectively. If the mobilities of electrons and hole are 2.3m 2 / volt-sec and 0.01m 2 /volt-sec, respectively, then semiconductor is
Truth table for system of four NAND gates as shown in figure is :
A light emitting diode has a voltage drop of 2V across it and passes a current of 10mA . When it operates with a 6V battery through a limiting resistor R , the value of R is :
The following configuration of gate is equivalent to
In the following combinations of logic gates, the outputs A, B and C are respectively :-
The process by which ac is converted into dc is known as
The diode shown in the circuit is a silicon diode. The potential difference between the points A and B will be
For a transistor the parameter β = 99. The value of the parameter α is
To get an output 1 from the circuit shown in the figure, the input must be
The output of OR gate is 1
For a common-emitter configuration, if α and β have their usual meanings, the correct relationship between α and β is
In an n-p-n transistor, the collector current is 10 mA, if 90% of the electrons emitted reach the collector, the emitter current I E and base current I B are given by
