الخميس، 2 يناير 2020

Electrical Engineering Practice bits -3

 Electrical Engineering Practice bits 




2.     An amplifier can be converted to an oscillator using
a.     Positive feedback
b.    Negative feedback
c.     Zero feedback
d.    Null feedback
3.     Which one of the following power semiconductor can be turned on and turnoff using gate
a.     SCR
b.    GTO
c.     MOSFET
d.    BJT
4.     The total resistance of a 90 ohms resistor and a 60 ohm resistor connected in parallel is
a.     16 ohm
b.    36 ohm
c.     45 ohm
d.    15 ohm
5.     In parallel RC circuit 1A flows through resistive branch and 1A through the capacitive branch. What is total current
a.     1A
b.    2A
c.     1.41A
d.    2.28A
6.     A 100/5A current transformer is used in conjunction with a 5A ammeter. If the ammeter reads 3A. the line current will be
a.     30A
b.    300A
c.     600A
d.    60A
7.     What is the formula for reactive power in 3-phase system
a.     3VLIL sin
b.    VphIph sin
c.     VLIL cos
d.    VLIL sin
8.     Mercury vapour lamp contain
a.     Neon and mercury
b.    Sodium and mercury
c.     Argon and mercury
d.    Argon and sodium
9.     Breather of a distribution transformer contain
a.     Calcium chloride
b.    Sodium chloride
c.     Calcium carbonate
d.    Dry air
10.  Very suitable motor for food mixer  is
a.     Capacitor start motor
b.    Repulsion motor
c.     Capacitor run motor
d.    Universal motor
11.  A constant speed dc motor is
a.     Differential compound motor
b.    Shunt motor
c.     Cumulative compound motor
d.    Series motor
12.  Magnetic and mechanical losses in dc machine are collectively known as
a.     Iron losses
b.    Stray losses
c.     Machine losses
d.    Hysteresis losses
13.  Unit of reluctance is
a.     Ampere turns/meter
b.    Web/meter2
c.     Amperes turns/web
d.    Web/ampere turns

14.  In an inductive circuit
a.     Current in phase with voltage
b.    Current leads voltage
c.     Current lags the voltage
d.    Voltage lags current
15.  When a lead acid cell is fully charged its anode is
a.     Lead
b.    Lead sulphate
c.     Lead peroxide
d.    Spongy lead
16.  For a 6 pole 1200rpm alternator the frequency will be
a.     60Hz
b.    50 Hz
c.     40 Hz
d.    70 Hz
17.  Gravity controlled instrument has to be kept
a.     horizontal
b.    vertical
c.     any position
d.    inclined
18.  what is the use of inter pole in DC generator
a.     to get large voltage
b.    to get large current
c.     to improve commutation
d.    to limit running current
19.  which diode used as voltage regulator
a.     PN junction
b.    Schoott key diode
c.     Photo diode
d.    Zener diode
20.  Rectification efficiency of half wave rectifier is
a.     802%
b.    40.6%
c.     32%
d.    86.2%

21.  The colour bands for resistor of value 47kΩ±5% tolerance is
a.     Yellow, violet, yellow, silver
b.    Yellow, violet, orange, silver
c.     Yellow, violet, orange, gold
d.    Yellow, violet, brown, gold

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Self Learners By Maniramakrishna

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