Answer: Ie = Ic + Ib IcRc + Vce + IeRe = Vcc Rib + Vbe + IeRe = Vcc Ib = 11.5/200 mA Rc + Re = 1.56 kilo ohm Rc = 560 Ohm
In the circuit, find the value of RC.
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Semiconductor Electronics: Materials, Devices and Simple Circuits
For the transistor circuit shown in Fig.14.19, evaluate VE, RB, RE given IC = 1 mA, VCE = 3V, VBE = 0.5 V and VCC = 12 V, β = 100.
Answer: $ {{I}_{C}}={{I}_{B}}+{{I}_{E}} $ $ {{I}_{B}}<<<{{I}_{C}} $ $ \therefore {{I}_{C}}={{I}_{E}} $ $ {{I}_{C}}=1mA(given) $ $ \therefore {{I}_{C}}={{I}_{E}}=1mA $ By Kirchhoff's loop...
Consider a box with three terminals on top of it:
Three components namely, two germanium diodes and one resistor are connected across these three terminals in some arrangement. A student performs an experiment in which any two of these three...
An X-OR gate has the following truth table:
A B Y 0 0 0 0 1 1 1 0 1 1 1 0 It is represented by the following logic relation Build this gate using AND, OR, and NOT gates. Answer: In given logic relation Y = AˉB + ABˉ =Y1Y2 Now, the logic...
Suppose a ‘n’-type wafer is created by doping Si crystal having 5 × 1028 atoms/m3 with 1ppm concentration of As. On the surface 200 ppm Boron is added to create the ‘P’ region in this wafer. Considering ni = 1.5 × 1016 m–3,
(i) Calculate the densities of the charge carriers in the n & p regions. (ii) Comment which charge carriers would contribute largely for the reverse saturation current when the diode is reverse...
Consider the circuit arrangement in which the input and output characteristics of NPN transistor in CE configuration
Select the values of RB and RC for a transistor whose VBE = 0.7 V, so that the transistor is operating at point Q as shown in the characteristics shown in the figure (b). Given that the input...
Assuming the ideal diode. Explain the waveform.
Answer: When signal 20sinωt provides an input voltage less than 5 volt (because after 5V, the diode will receive a positive voltage at its P-junction), the diode will be in reverse bias, and the...
Draw the output signals C1 and C2 in the given combination of gates in the figure.
In the circuit shown in the figure, when the input voltage of the base resistance is 10V, Vbe is zero and Vce is also zero. Find the values of Ib, Ic and β.
Answer: As $ {{V}_{BE}}=0 $, the potential drop across $ {{R}_{B}} $ is 10 Volts. $ {{I}_{B}}=\frac{10}{400\times {{10}^{3}}}=25\mu A $ Now, as $ {{V}_{CE}}=0 $, The potenial drop across $...
If each diode in the figure has a forward bias resistance of 25Ω and infinite resistance in reverse bias, what will be the values of the current I1, I2, I3 and I4?
Answer: Because the diode in that branch is reverse biased, I3 is zero. I3 = 0 We know that the resistance in AB = 150 ohms and the resistance in EF = 150 ohms and AB is parallel to EF Therefore,...
A Zener of power rating 1 W is to be used as a voltage regulator. If Zener has a breakdown of 5V and it has to regulate voltage which fluctuated between 3V and 7V, what should be the value of Rs for safe operation in the figure?
Answer: According to the question, Power = 1W and Zener breakdown voltage = 5V We are given that the minimum voltage = 3V and the maximum voltage = 7V $ {{I}_{\max }}=\frac{P}{{{V}_{z}}}=\frac{1}{5}...
Write the truth table for the circuit shown in the figure. Name the gate that the circuit resembles.
Answer: The given circuit is AND and the truth table is: A B X = A.B 0 0 0 0 1 0 1 0 0 1 1 1
Explain why elemental semiconductor cannot be used to make visible LEDs.
Answer: The bandgap in an elemental conductor is such that the emissions are infrared rather than visible. Elemental semiconductors cannot be used to make visible LEDs. This is because the energy...
How would you set up a circuit to obtain NOT gate using a transistor?
Answer: a) There is only one input and only one output b) By making use of the Boolean expression c) Realization of NOT gate d) Making use of the truth table The NOT gate is a single-input,...
Two car garages have a common gate which needs to open automatically when a car enters either of the garages or cars enter both. Devise a circuit that resembles this situation using diodes for this situation.
Answer: When an automobile approaches the gate, one or both gates are open. As a result, the OR gate produces the required result. The following is a truth table for the same: A B Y = A + B 0 0 0 0...
If the resistance R1 is increased, how will the readings of the ammeter and voltmeter change?
Answer: From the circuit diagram, we have IbR1 + Vbe = Vbb Expression for the base current gives us Ib = Vbb – Vbe/R1 It can be seen that Ib is inversely proportional to R1 The reading of the...
Three photodiodes D1, D2 and D3 are made of semiconductors having band gaps of 2.5eV, 2eV and 3eV, respectively. Which ones will be able to detect light of wavelength 6000 Ao?
Answer: According to the question, the wavelength is: λ = 6000 Ao = 6000 × 10-10m Expression for the energy of the light photon is as follows: E = hc/ λ Upon substituting the values of h, c and...
(i) Name the type of a diode whose characteristics are shown in the figure (a) and in the figure (b)
(ii) What does the point P in the figure (a) represent? (iii) What does the points P and Q in the figure (b) represent? Answer: (i) Figure a) depicts the Zener diode's characteristics, whereas...
In a CE transistor amplifier there is a current and voltage gain associated with the circuit. In other words, there is a power gain. Considering power a measure of energy, does the circuit violate conservation of energy?
Answer: The DC supply is connected to the CE transistor amplifier to provide energy to the signal. As a result, the CE configuration amplifier has a significant power gain. The extra power necessary...
The amplifiers X, Y and Z are connected in series. If the voltage gains of X, Y and Z are 10, 20 and 30, respectively and the input signal is 1 mV peak value, then what is the output signal voltage (peak value)
(i) if dc supply voltage is 10V? (ii) if dc supply voltage is 5V? Answer: According to the question, we can write Voltage gain in X = vx = 10 Voltage gain in Y = vy = 20 Voltage gain in Z = vz = 30...
Draw the output waveform across the resistor in the figure.
The waveform formed across the resistance diode conducts when the diode is forward biassed in the given circuit, hence the output will be only when the input +1V is between t1 and t2. As a result,...
Can the potential barrier across a p-n junction be measured by simply connecting a voltmeter across the junction?
Answer: We can't use a voltmeter to detect the potential barrier across a p-n junction because the voltmeter's resistance must be very high relative to the junction resistance, which is almost...
Sn, C, and Si, Ge are all group XIV elements. Yet, Sn is a conductor, C is an insulator while Si and Ge are semiconductors. Why?
Answer: If there is no energy gap between the conduction and valence bands in an atom's energy band diagram, the material will conduct current. This energy gap narrows when the material transitions...
Why are elemental dopants for Silicon or Germanium usually chosen from group XIII or group XV?
Answer: Because the size of the dopant must be compatible with the semiconductor and they must form covalent bonds. The elemental dopants for silicon or germanium are usually chosen from groups XIII...
The breakdown in a reverse-biased p–n junction diode is more likely to occur due to
(a) large velocity of the minority charge carriers if the doping concentration is small (b) large velocity of the minority charge carriers if the doping concentration is large (c) strong electric...
To reduce the ripples in a rectifier circuit with capacitor filter
(a) RL should be increased (b) input frequency should be decreased (c) input frequency should be increased (d) capacitors with high capacitance should be used Answer: The correct options are: (a) RL...
What happens during regulation action of a Zener diode?
(a) The current in and voltage across the Zenor remains fixed (b) The current through the series Resistance (Rs ) changes (c) The Zener resistance is constant (d) The resistance offered by the Zener...
In the depletion region of a diode
(a) there are no mobile charges (b) equal number of holes and electrons exist, making the region neutral (c) recombination of holes and electrons has taken place (d) immobile charged ions exist...
In an NPN transistor circuit, the collector current is 10mA. If 95 per cent of the electrons emitted reaches the collector, which of the following statements are true?
(a) The emitter current will be 8 mA (b) The emitter current will be 10.53 mA (c) The base current will be 0.53 mA (d) The base current will be 2 mA Answer: The correct options are: (b) The emitter...
In the figure shows the transfer characteristics of a base biased CE transistor. Which of the following statements are true?
(a) At Vi = 0.4V, transistor is in active state (b) At Vi = 1V, it can be used as an amplifier (c) At Vi = 0. .5V, it can be used as a switch turned off (d) At Vi = 2.5V, it can be used as a switch...
Consider an NPN transistor with its base-emitter junction forward biased and collector-base junction reverse biased. Which of the following statements are true?
(a) Electrons crossover from emitter to collector (b) Holes move from base to collector (c) Electrons move from emitter to base (d) Electrons from emitter move out of base without going to the...
When an electric field is applied across a semiconductor
(a) electrons move from lower energy level to higher energy level in the conduction band (b) electrons move from higher energy level to lower energy level in the conduction band (c) holes in the...
Truth table for the given circuit in the figure is
(a) A B E 0 0 1 0 1 0 1 0 1 1 1 0 (b) A B E 0 0 1 0 1 0 1 0 0 1 1 1 (c) A B E 0 0 0 0 1 1 1 0 0 1 1 1 (d) A B E 0 0 0 0 1 1 1 0 1 1 1 0 Answer: The correct option is (c) A B E 0 0 0 0 1 1 1 0 0 1 1...
In the circuit shown in the figure, if the diode forward voltage drop is 0.3 V, the voltage difference between A and B is
(a) 1.3 V (b) 2.3 V (c) 0 (d) 0.5 V Answer: The correct option is (b) 2.3 V Explanation: Let V represent the potential difference between A and B, then we can write: V - 0.3 = (5 +5) x 103 x (0.2 x...
The output of the given circuit in the figure
(a) would be zero at all times (b) would be like a half-wave rectifier with positive cycles in output (c) would be like a half-wave rectifier with negative cycles in output (d) would be like that of...
Hole is
(a) an anti-particle of the electron (b) a vacancy created when an electron leaves a covalent bond (c) absence of free electrons (d) an artificially created particle Answer: The correct option is...
A 220 V A.C. supply is connected between points A and B in the figure. What will be the potential difference V across the capacitor?
(a) 220V (b) 110V (c) 0V (d) 220 √2 V Answer: The correct option is (d) 220 √2 V Explanation: V(max) will be the potential difference across the capacitor. It is given by: ${{V}_{\max...
In the figure, assuming the diodes to be ideal,
(a) D1 is forward biased and D2 is reverse biased and hence current flows from A to B (b) D2 is forward biased and D1 is reverse biased and hence no current flows from B to A and vice versa (c) D1...
In the figure, Vo is the potential barrier across a p-n junction, when no battery is connected across the junction
(a) 1 and 3 both correspond to forward bias of junction (b) 3 corresponds to forward bias of junction and 1 corresponds to reverse bias of junction (c) 1 corresponds to forward bias and 3...
The conductivity of a semiconductor increases with increase in temperature because
(a) number density of free current carriers increases (b) relaxation time increases (c) both number density of carriers and relaxation time increase (d) number density of current carriers...