A 3-ohm load is coupled to a transistor amplifier through a step-down transformer. If the D.C resistance of the primary winding is 300Ω and the output resistance of the amplifier is 3KΩ, what shoul...
Np/Ns=40 0.0%
Np/Ns=20 0.0%
Np/Ns=30 66.0%
Np/Ns=10 33.0%
A D.C milliammeter connected to a half-wave rectifier supplying a maximum current of 10mA will read _____.
10 mA 100.0%
20 mA 0.0%
5 mA 0.0%
3.18 mA 0.0%
A P-type material is _____.
positively charged 100.0%
negatively charged 0.0%
electrically neutral 0.0%
none of the above 0.0%
A reversed biased P-N junction has a resistance of the order of _____.
Ω 0.0%
KΩ 0.0%
MΩ 100.0%
mΩ 0.0%
A three-stage amplifier has a first-stage voltage gain of 100, a second stage voltage gain of 200 and a third stage gain of 400. The total voltage gain in db will be _____.
130 dB 0.0%
140 dB 100.0%
132 dB 0.0%
138 dB 0.0%
A transistor amplifier has 4v,2mA as the operating point. For faithful amplification, the collector current due to signal alone should not exceed _____.
2mA 100.0%
1mA 0.0%
4mA 0.0%
8mA 0.0%
A triac can pass a portion of _____.
positive half-cycle through the load 0.0%
negative half-cycle through the load 0.0%
both positive and negative half-cycles through the load 100.0%
None of the above 0.0%
A vacuum tube conducts current _____.
from the cathode to the anode 0.0%
from the anode to the cathode 100.0%
in both the above directions 0.0%
alternately in both directions 0.0%
A varactor diode can function as a variable capacitor with a________ forward bias.
very slight 0.0%
moderate 0.0%
heavy 100.0%
According to the Barkhausen criterion for oscillators_______. A – open loop gain β – feed back factor
Aβ < 1 0.0%
Aβ > 1 100.0%
Aβ = 1 0.0%
Aβ ≤ 1 0.0%
An :FET is a _____.
bipolar device 50.0%
tripolar device 0.0%
unipolar device 50.0%
An A.C supply of 230v is applied to a half wave rectifier circuit through a transformer of turn ratio 10:1. Its D.C voltage output will be _____.
5v 0.0%
12v 0.0%
10.36v 100.0%
5.18v 0.0%
An FET has ________ temperature co-efficient of resistance.
0 0.0%
positive 0.0%
negative 100.0%
An FET has the following parameters IDSS = 32mA , VGS ( off ) = -8V , VGS = -4.5V. What will be the drain current?
5.2 mA 0.0%
6.12 mA 100.0%
7.03 mA 0.0%
7.45 mA 0.0%
An SCR combines the features of_____.
a rectifier and an amplifier 0.0%
a rectifier and a transistor 100.0%
a rectifier and an oscillator 0.0%
a rectifier and an inverter 0.0%
An SCR is a solid state equivalent of a _____.
triode 0.0%
pentode 100.0%
thyratron 0.0%
diode 0.0%
At parallel resonance, a tuned circuit offers an impedance of _____.
C/LR 0.0%
R/LC 50.0%
L/CR 50.0%
2L/CR 0.0%
For an R-C phase shift oscillator , the frequency of oscillation will be given as _____.
fo = 1/2П√RC 50.0%
fo = 1/2П√6RC 50.0%
fo = 1/√2ПRC 0.0%
fo = 2/√2ПRC 0.0%
For faithful amplification, VBE must not fall below _____.
0.9v for si transistors 0.0%
0.5v for si transistors 0.0%
0.3v for si transistors 0.0%
0.7v for si transistors 100.0%
For good stabilization of the operating point in a voltage divider bias, the current I, flowing through potential dividers R1 and R2, should be equal to or greater than _____. (IB-base current)
2IB 0.0%
10IB 100.0%
4IB 0.0%
IB/2 0.0%
Hartley oscillator is _____.
an RC oscillator 0.0%
an LC oscillator 100.0%
a Crystal oscillator 0.0%
If a circuit of full-wave centre-tapped rectifier with capacitor filter employs a load RL = 100Ω, and C = 1050µF and the frequency is 50HZ , what would be the ripple factor?
40% 0.0%
30% 0.0%
22% 100.0%
27% 0.0%
If in a transistor , Ic = 9.5mA , Ie = 10mA , the value of α will be _____.
0.95 100.0%
10 0.0%
9.5 0.0%
0.095 0.0%
If in a transistor IE = 10.5mA , IC = 10mA,the value of β will be _____.
0.2 0.0%
200 50.0%
100 0.0%
20 50.0%
If in a transistor VCB= 4V , VBE = 0.7V, the VCE will be equal to _____.
4.7v 100.0%
5.4v 0.0%
3.3v 0.0%
0.7v 0.0%
If the A.C input to a half-wave rectifier has an R.M.S valve of 400/√2 v, the peak inverse voltage will be _____.
400 v 0.0%
400√2 v 100.0%
800√2 v 0.0%
800/√2 v 0.0%
If the collector supply voltage is 10v, the collector cut off voltage under D.C conditions will be _____.
5v 0.0%
10v 100.0%
20v 0.0%
30v 0.0%
If the input to a differentiating circuit is a square wave, the output will be _____.
rectangular 0.0%
spiked 50.0%
triangular 50.0%
sinusoidal 0.0%
If the input to an integrating circuit is a square wave, the output will be _____.
triangular 0.0%
rectangular 0.0%
saw-tooth 100.0%
spiked 0.0%
If the reverse bias on the gate of an FET is increased , the width of the conducting channel will _____.
increase 0.0%
decrease 100.0%
remain constant 0.0%
In an R-C phase shift oscillator, an R-C network is designed to introduce a phase shift of _____ .
300 50.0%
600 0.0%
900 50.0%
1800 0.0%
In the collector feedback biasing, β = 57 , RC = 1 kΩ , IB = 60µA and VCB = 4.5V. The value of the stability factor will be _____.
30.4 0.0%
32.9 100.0%
57 0.0%
4.5 0.0%
In the d.c. equivalent circuit of a transistor amplifier , the capacitors are regarded as _____.
Open 0.0%
Short 0.0%
Sometimes open and sometimes short 0.0%
Unchanged 100.0%
In the enhancement mode (MOSFET) , conductivity increases _____.
with the decrease in positive gate voltage 0.0%
with the increase in positive gate voltage 0.0%
with the decrease in negative gate voltage 0.0%
with the increase in negative gate voltage 100.0%
Radio frequencies have their range above _____.
20KHZ 100.0%
50KHZ 0.0%
100KHZ 0.0%
200KHZ 0.0%
The complementary MOS(CMOS) uses _____.
only n-channel devices in the circuit 0.0%
only p- channel devices in the circuit 0.0%
both n and p channel devices in the circuit 100.0%
None of the above 0.0%
The ideal value of the stability factor is _____.
0 0.0%
10 0.0%
1 100.0%
100 0.0%
The impedance of a parallel tuned circuit at resonance is _____.
0 0.0%
low 100.0%
very high 0.0%
very low 0.0%
The input and output voltages of a CE transistor amplifier are _____.
in phase 0.0%
90° out of phase 0.0%
180° out of phase 100.0%
120° out of phase 0.0%
The maximum efficiency of a full wave rectifier is _____.
40% 0.0%
81.2% 50.0%
90% 0.0%
99% 50.0%
The maximum value of AC voltage appearing across the secondary of a transformer in a bridge circuit using a vacuum tube is 400 v. The peak inverse voltage of the diode should be _____.
200 v 0%
800 v 0%
400 v 0%
600 v 0%
The most commonly used semiconductor in solid state devices is _____.
germanium 0%
carbon 0%
silicon 0%
phosphorus 0%
The output characteristics of an FET closely resemble the plate characteristics of a________ valve.
diode 0.0%
triode 0.0%
tetrode 0.0%
pentode 100.0%
The output frequency of a half-wave rectifier is _____.
double the input A.C frequency 0.0%
half the input A.C frequency 0.0%
equal to the input A.C frequency 100.0%
None of the above 0.0%
The overall gain of a multistage amplifier is 140. When negative feedback is applied, the gain is reduced to 17.5. The fraction of the output that is feedback to the input will be _____.
1/30 0.0%
1/20 100.0%
1/10 0.0%
1/5 0.0%
The Q-factor of a parallel tuned circuit is given by _____.
1/R√C/L 100.0%
R√L/C 0.0%
1/R√L/C 0.0%
R√C/L 0.0%
The range of LC oscillators is _____.
20 HZ to 100KHZ 0%
10 HZ to 20 HZ 0%
100KHZ to a few GHZ 0%
The relationship among bandwidth, resonant frequency and Q of a tuned circuit is _____.
BW = Q/fr 0.0%
BW = Q fr 0.0%
BW = fr√Q 0.0%
BW = fr/Q 100.0%
The required gain of an amplifier for sustained oscillation in the wein bridge oscillator is _____.
A 2 0%
A 1 0%
A 3 0%
None of the above 0%
The resonant circuit has ___________ impedance at the resonant frequency.
a capacitive 0%
an inductive 0%
a resistive 0%
The slope of the D.C load line of a transistor circuit having a collector load Rc is _____.
Rc 0.0%
1/Rc 100.0%
-1/Rc 0.0%
2Rc 0.0%
The stability factor of a biasing circuit is 10. What does it mean?
Ic changes 10 times as munch as any change in Ico(leakage current) 100.0%
Ib changes 10 times as much as any change in Ico 0.0%
Ie change 10 times as munch as any change in Ico 0.0%
The V-I characteristics of a triac in the first and third quadrants are essentially identical to those of _______ in the first quadrant
a transistor 0.0%
a UJT 0.0%
a zener diode 0.0%
an SCR 100.0%
Tuned amplifiers are generally operated as
class A amplifiers 0.0%
class B amplifiers 0.0%
class AB amplifiers 0.0%
class C amplifiesrs 100.0%
Tuned amplifiers are used for the amplification of _____.
audio frequencies 0.0%
RF 100.0%
very low frequencies 0.0%
very high frequencies 0.0%
Tuning is generally accomplished by varying _____.
L(inductor) 0.0%
C(capacitor) 0.0%
both L and C 100.0%
R(resistor) 0.0%
Two identical germanium diodes are connected in series opposition. A 10V battery is impressed upon this series arrangement. What will be the voltage across each diode room temperature if the Zener ...
VD1= 0.2V , VD2 = 9.8V 100.0%
VD1 = 10V , VD2 = 0V 0.0%
VD1 = 0V , VD2 = 10V 0.0%
VD1 = 9.8V , VD2 = 0.2V 0.0%
Vacuum tubes are _____.
linear devices 0.0%
non-linear devices 0.0%
both linear and non-linear under different conditions 100.0%
We have to match a 16-ohm speaker to an amplifier so that the effective load resistance is 10 KΩ. What should be the transformer turn ratio?
Np/Ns=50 0%
Np/Ns=25 0%
Np/Ns=75 0%
Np/Ns=12.5 0%
What would be the gain of a negative feedback amplifier with an internal gain A=100 and a feedback factor m=0.9?
1.09 100.0%
12 0.0%
5.5 0.0%
7 0.0%
When a transistor has to act as a switch, it must operate in _____.
the active region 0.0%
the cut-off region 0.0%
the saturation region 0.0%
both the cut off and the saturation regions 100.0%
When a transistor is driven to saturation, ideally, the Vce is _____.
VCC 0.0%
VCC/2 0.0%
0 100.0%
2VCC 0.0%
Which coupling does the final stage of a multistage amplifier use?
direct 0%
transformer 0%
RC 0%
None of the above 0%
Which device has the highest input impedance?
MOSFET 0%
FET 0%
BJT 0%
SCR 0%
Which of the following conditions must a transistor fulfill to act as an amplifier?
Base-emitter junction reverse biased and base-collector junction forward biased 0%
Base-emitter junction forward biased and base-collector junction reverse biased 0%
Emitter-collector junction forward biased and base- collector junction reverse biased 0%
Base-collector junction forward biased and emitter-collector junction reverse biased 0%
Which of the following configurations of a transistor is preferred as an amplifier?
common-collector 0%
common- base 0%
common-emitter 0%
None of the above 0%
Which of the following is used to provide current in vacuum tubes?
protons 0.0%
ions 0.0%
electrons 100.0%
neutrons 0.0%
Which of the following multivibrators is a square wave oscillator?
astable 0%
monostable 0%
bistable 0%
None of above 0%
Which of the following parameters is a measure of a vacuum tube's amplification capability?
transresistance 0%
impedance 0%
conductance 0%
transconductance 0%
Which one of the following is a non-feedback type oscillator?
Wein bridge oscillator 0%
Hartley oscillator 0%
UJT relaxation oscillator 0%
Colpitts oscillator 0%
Which one of the following is Shockley's equation?
ID = IDSS [1-VGS/VP]2 0%
IDSS = ID [1-VGS/VP]2 0%
VP = IP [1-VGS/IDSS]2 0%
VGS = VP [1-ID/IDSS]2 0%
Why is the control grid of a tube always held at negative potential W.R.T cathode.?
in order to avoid heating of the tube 0.0%
in order to obtain faithful amplification 100.0%
in order to set its operating point 0.0%
None of the above 0.0%