JEE Questions for Physics Semiconductor Devices Quiz 20 - MCQExams.com

In a triode valve
  • If the grid voltage is zero, then plate current will be zero
  • If the temperature of filament is doubled, then the thermionic current will also be doubled
  • If the temperature of filament is doubled, then the thermionic current will nearly be four times
  • At a definite grid voltage the plate current varies with plate voltage according to Omh's law

Physics-Semiconductor Devices-88365.png
  • 100 kilo-ohms static
  • 1000 kilo-ohms static
  • 1000 kilo-ohms dynamic
  • 100 kilo-ohms dynamic
A triode has a mutual conductance of 2 × 10–3 mho andan amplification factor of 50. The anode is connected through a resistance of 25 × 103 ohms to a 250 volts supply. The voltage gain of this amplifier is
  • 50
  • 25
  • 100
  • 12.5
14 × 1015 electrons reach the anode per second. If thepower consumed is 448 milliwatts, then the plate (anode) voltage is
  • 150 V
  • 200 V
  • 14 × 448 V
  • 448/14 V
In the circuit of a triode valve, there is no change in the plate current, when the plate potential is increased from 200 volt to 220 volt and the grid potential is decreased from – 0.5 volt to – 1.3 volt. The amplification factor of this valve is
  • 15
  • 20
  • 25
  • 35
If the amplification factor of a triode (μ) is 22 and its plate resistance is 6600 ohm, then the mutual conductance of this valve in mho is

  • Physics-Semiconductor Devices-88370.png
  • 25 × 10–2
  • 2.5 × 10–2
  • 0.25 × 10–2
The ripple factor in a half wave rectifier is
  • 1.21
  • 0.48
  • 0.6
  • None of these
The value of plate current in the given circuit diagram will be
Physics-Semiconductor Devices-88376.png
  • 3 mA
  • 8 mA
  • 13 mA
  • 18 mA
Correct relation for triode is

  • Physics-Semiconductor Devices-88378.png
  • 2)
    Physics-Semiconductor Devices-88379.png

  • Physics-Semiconductor Devices-88380.png
  • None of these
Following is the relation between current and charge I = AT2eq/VL, then value of VL will be

  • Physics-Semiconductor Devices-88381.png
  • 2)
    Physics-Semiconductor Devices-88382.png

  • Physics-Semiconductor Devices-88383.png

  • Physics-Semiconductor Devices-88384.png
Which one is correct relation for thermionic emission?
  • J = AT1/2 – eϕ/kT
  • J = AT2e–ϕ /kT
  • J = AT3/2e–ϕ /kT
  • J = AT2e–ϕ /2kT
When plate voltage in diode valve is increased from 100 volt to 150 volt, then plate current increases from 7.5 mA to 12 mA. The dynamic plate resistance will be
  • 10 k Ω
  • 11 k Ω
  • 15 k Ω
  • 11.1 k Ω
In a diode valve, the state of saturation can be obtainedeasily by
  • High plate voltage and high filament current
  • Low filament current and high plate voltage
  • Low plate voltage and high cathode temperature
  • High filament current and high plate voltage
Plate resistance of two triode valves is 2 k Ω and 4 kΩ, amplification factor of each of the valves is 40. The ratio of voltage amplification, when used with 4 kΩ load resistance, will be
  • 10
  • 4/3
  • 3/4
  • 16/3
Which of the following does not vary with plate or grid voltages
  • gm
  • Rp
  • μ
  • Each of them varies
The amplification factor of a triode is 18 and its plate resistance is 8 × 103Ω. A load resistance of 104Ω isconnected in the plate circuit. The voltage gain will be
  • 30
  • 20
  • 10
  • 1
The transconductance of a triode amplifier is 2.5 mili mho having plate resistance of 20 kΩ, amplification 10. Find the load resistance
  • 5 kΩ
  • 25 kΩ
  • 20 kΩ
  • 50 kΩ
A silicon specimen is made into a P–type semi-conductor by dopping, on an average, one indium atom per 5 × 107 silicon atoms. If the number density ofatoms in the silicon specimen is 5 × 1028 atoms/m3, then the number of acceptor atoms in silicon per cubiccentimetre will be
  • 2.5 × 1030 atoms/m3
  • 1.0 × 1013 atoms/m3
  • 1.0 × 1015 atoms/m3
  • 2.5 × 1036 atoms/m3
The probability of electrons to be found in the conduction band of an intrinsic semiconductor at afinite temperature
  • Decreases exponentially with increasing band gap
  • Increases exponentially with increasing band gap
  • Decreases with increasing temperature
  • Is independent of the temperature and the band gap
In PN–junction diode the reverse saturation current is 10–5 amp at 27°C. The forward current for a voltage of 0.2 volt is
[exp (7.= 2038.6, k = 1.4 × 10–23J/K]
  • 2037.6 × 10–3 amp
  • 203.76 × 10–3 amp
  • 20.376 × 10–3 amp
  • 2.0376 × 103 amp
In the circuit, if the forward voltage drop for the diodeis 0.5 V, the current will be
Physics-Semiconductor Devices-88395.png
  • 3.4 mA
  • 2 mA
  • 2.5 mA
  • 3 mA
P–type semiconductor has acceptor levels 57 meV above the valence band. The maximum wavelength of light required to create a hole is (Planck\'s constant h = 6.6 × 10–34J – s)
  • 57 Å
  • 57 × 10–3Å
  • 217100 Å
  • 11.61 × 10–33Å
Current in the circuit will be
Physics-Semiconductor Devices-88398.png

  • Physics-Semiconductor Devices-88399.png
  • 2)
    Physics-Semiconductor Devices-88400.png

  • Physics-Semiconductor Devices-88401.png

  • Physics-Semiconductor Devices-88402.png
The diode used in the circuit shown in the figure has a constant voltage drop of 0.5 V at all currents and a maximum power rating of 100 milliwatts. What should be the value of the resistor R, connected in series with the diode for obtaining maximum current?
Physics-Semiconductor Devices-88404.png
  • 1.5 Ω
  • 5 Ω
  • 6.67 Ω
  • 200 Ω
In the following common emitter configuration an NPN transistor with current gain β = 100 is used. The output voltage of the amplifier will be
Physics-Semiconductor Devices-88406.png
  • 10 mV
  • 0.1 V
  • 1.0 V
  • 10 V
In semiconductor the concentrations of electrons and holes are 8 × 1018 /m3 and 5 × 1018 /m respectively. Ifthe mobilities of electrons and holes are 2.3 m2/volt –s and 0.01 m2/volt –s respectively, then semiconductor is
  • N–type and its resistivity is 0.34 ohm–metre
  • P–type and its resistivity is 0.034 ohm–metre
  • N–type and its resistivity is 0.034 ohm–metre
  • P–type and its resistivity is 3.40 ohm–metre
A sinusoidal voltage of peak value 200 volt is connected to a diode and resistor R in the circuit shown so that half wave rectification occurs. If the forward resistance of the diode is negligible compared to R the rms voltage (in volt) across R is approximately
Physics-Semiconductor Devices-88409.png
  • 200
  • 100

  • Physics-Semiconductor Devices-88410.png
  • 280
The junction diode in the following circuit requires a minimum current of 1 mA to be above the knee point (0.7 V) of its I–V characteristic curve. The voltage across the diode is independent of current above the knee point. If VB = 5 V, then the maximum value of R so that the voltage is above the knee point, will be
Physics-Semiconductor Devices-88412.png
  • 4.3 k Ω
  • 860 kΩ
  • 4.3 Ω
  • 860 Ω
In the circuit given below, V(t) is the sinusoidal voltage source, voltage drop VAB (t) across the resistance R is
Physics-Semiconductor Devices-88414.png
  • Is half wave rectified
  • Is full wave rectified
  • Has the same peak value in the positive and negative half cycles
  • Has different peak values during positive and negative half cycle
The peak voltage in the output of a half-wave diode rectifier fed with a sinusoidal signal without filter is10 V. The D.0 component of the output voltage is

  • Physics-Semiconductor Devices-88415.png
  • 10 / πV
  • 10 V
  • 20 / πV
Select the outputs Y of the combination of gates shown below for inputs A = 1, B = 0; A = 1, B = 1 and A = 0, B = 0 respectively
Physics-Semiconductor Devices-88417.png
  • (0 1
  • (0 0 1)
  • (1 0
  • (1 1 1)
In the following circuits PN–junction diodes D1, D2 and D3 are ideal for the following potentials of A and B. The correct increasing order of resistance between A and B will be
Physics-Semiconductor Devices-88418.png
  • (i) < (ii) < (iii)
  • (iii) < (ii) < (i)
  • (ii) = (iii) < (i)
  • (i) = (iii) < (ii)
Find VAB
Physics-Semiconductor Devices-88420.png
  • 10 V
  • 20 V
  • 30 V
  • None of these
A diode is connected to 220 V (rms) A.C in series with a capacitor as shown in figure. The voltage across thecapacitor is
Physics-Semiconductor Devices-88422.png
  • 220 V
  • 110 V
  • 311.1 V

  • Physics-Semiconductor Devices-88423.png

Physics-Semiconductor Devices-88425.png
  • 0.25 A
  • 0.45 A
  • 0.56 A
  • 0.64 A
The contribution in the total current flowing through a semiconductor due to electrons and holes are 3/4 and 1/4 respectively. If the drift velocity of electrons is 5/2 times that of holes at this temperature, then the ratio of concentration of electrons and holes is
  • 6 : 5
  • 5 : 6
  • 3 : 2
  • 2 : 3
The following configuration of gate is equivalent to
Physics-Semiconductor Devices-88428.png
  • NAND
  • XOR
  • OR
  • None of these
Figure gives a system of logic gates. From the study of truth table it can be found that to produce a high output (at R, we must have
Physics-Semiconductor Devices-88430.png
  • X = 0, Y = 1
  • X = 1, Y = 1
  • X = 1,Y = 0
  • X = 0, Y = 0
The combination of gates shown below produces
Physics-Semiconductor Devices-88432.png
  • AND gate
  • XOR gate
  • NOR gate
  • NAND gate
The figure shows two NAND gates followed by a NOR gate. The system is equivalent to the following logic gate
Physics-Semiconductor Devices-88434.png
  • OR
  • AND
  • NAND
  • None of the above
The voltage gain of the following amplifier is
Physics-Semiconductor Devices-88436.png
  • 10
  • 100
  • 1000
  • 9.9
Amplification factor of a triode is 10. When the plate potential is 200 volt and grid potential is – 4 volt, then the plate current of 4 mA is observed. If plate potential is changed to 160 volt and grid potential is kept at – 7 volt, then the plate current will be
  • 1.69 mA
  • 3.95 mA
  • 2.87 mA
  • 7.02 mA
On applying a potential of –1 volt at the grid of a triode, the following relation between plate voltage Vp (volt) and plate current Ip (in mA) is found Ip = 0.125 Vp – 7.5. If on applying –3 volt potential at grid and 300 V potential at plate, the plate current is found to be 5 mA, then amplification factor of the triode is
  • 100
  • 50
  • 30
  • 20
The temperature (T) dependence on resistivity (ρ) of asemiconductor is represented by

  • Physics-Semiconductor Devices-88440.png
  • 2)
    Physics-Semiconductor Devices-88441.png

  • Physics-Semiconductor Devices-88442.png

  • Physics-Semiconductor Devices-88443.png
In a forward biased PN–junction diode, the potentialbarrier in the depletion region is of the form

  • Physics-Semiconductor Devices-88444.png
  • 2)
    Physics-Semiconductor Devices-88445.png

  • Physics-Semiconductor Devices-88446.png

  • Physics-Semiconductor Devices-88447.png
The current between charge density and distance near P–N junction will be

  • Physics-Semiconductor Devices-88448.png
  • 2)
    Physics-Semiconductor Devices-88449.png

  • Physics-Semiconductor Devices-88450.png

  • Physics-Semiconductor Devices-88451.png
The resistance of a germanium junction diode whose V – I is shown in figure is (Vk = 0.3V )
Physics-Semiconductor Devices-88453.png
  • 5 k Ω
  • 0.2 kΩ
  • 2.3 kΩ

  • Physics-Semiconductor Devices-88454.png
The output in the circuit of figure is taken across a capacitor. It is as shown in figure
Physics-Semiconductor Devices-88456.png

  • Physics-Semiconductor Devices-88457.png
  • 2)
    Physics-Semiconductor Devices-88458.png

  • Physics-Semiconductor Devices-88459.png

  • Physics-Semiconductor Devices-88460.png
Assertion The temperature coefficient of resistance is positive for metals and negative for P-type semiconductor
Reason The effective charge carriers in metals are negatively charged whereas in P-type semiconductor they are positively charged.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion
  • If Assertion is true but Reason is false
  • If the Assertion and Reason both are false
  • If Assertion is false but Reason is true
A full wave rectifier circuit along with the input and output voltages is shown in the figure
The contribution to output voltage from diode –2 is
Physics-Semiconductor Devices-88462.png
  • A, C
  • B, D
  • B, C
  • A, D
0:0:1


Answered Not Answered Not Visited Correct : 0 Incorrect : 0

Practice Physics Quiz Questions and Answers