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1.0.0
MCQ
4661. Which of the following lamp has minimum initial cost of installation but maximum running cost?
incandescent
fluorescent
mercury vapour
sodium vapour
ব্যাখ্যা: Incandescent lamp has higher resistance compare to other lamps. As a result more electricity is used to run this blubs. So the running cost is high.
4662. An air-core choke coil and an electric bulb are connected in series with ac mains. On introducing soft iron bar in the coil, the intensity of light will-
fluctuate
remain unchanged
increase
decrease
4663. For Y-connection under balanced condition the line to line voltage is-
same as the phase voltage
√3 times the phase voltage
√2 times the phase voltage
none of the above
4664. One watt-hour is equal to-
360 Joule
300 Joule
3000 Joule
3600 Joule
4665. What would be the charge of a capacitor 10μF when connected with 20V supply?
200μc
300μc
6200μc
30μc
4666. How long does it take 50 µC of charge to pass a point in a circuit if the current flow is 15 mA?
3.33 x 10^3s
6 x 10^3s
6.33 × 10^3s
2s
4667. Which of the following connections is best suited for 3-phase, 4-wire service?
Δ-Δ
Y-Y
Δ-Υ
Y-A
ব্যাখ্যা: Δ-Υ connection is popular for both the step (transmission side, high voltage) and step-down (distribution zide, low voltage) applications
4668. In the maximum value of a current of a circuit is 1 amp (sinusoidal wave). What is the R.M.S. value?
1 Amp
0.637 Amp
0.707 Amp
1.5 Amp
4669. A capacitor opposes---
charge in current
charge in voltage
both charge in current and voltage
none
4670. One Horse Power is equal to-
5.50 Foot pound/Second
55.00 Foot pound/Second
550 Foot pound/Second
5500 Foot pound/Second
4671. Three equal resistor of 100 is connected in series across a source of Emf 30V. What would be the power consumed by each resistor?
10W
90W
30W
60W
4672. For an R-L load ---
Active power is greater than apparent power
Reactive power is greater than apparent power
Apparent power is greater than both Active and Reactive power
All are equal
4673. If the power factor of a circuit is unity, its reactive power is-
a maximum
zero
quantity
equal to FR
4674. What quantity of charage must be delivered by a battery with a potential difference of 100 V to do 500) of work?
5C
50C
0.5C
500C
4675. The power factor of an ordinary electric bulb is--
Zero
Unity
Slightly more than zero
Slightly less than unity
ব্যাখ্যা: Basically ordinary electric bulb are resistive load. As resistive load they have unity power factor.
4676. The d.c. series motor should never be switched on at no load because-
the field current is zero
the machine does not pickup
the speed becomes dangerously high
it will take too long to accelerate
ব্যাখ্যা: No mechanical load on the series motor, the current is low, the counter-EMF produced by field winding is weak and so the armature most turn faster to produce sufficient counter EMF to balance the supply voltage. The motor can be damage by overspeed.
4677. The power of an AC circuit is given by-
VI cosθ
FZ
VI sinθ
FXL
4678. If positive phase sequence of 3-0 load is 'abc', the negative sequence is-
bac
cba
ach
all of the above
4679. The capacitance of a capacitor is influented by-
Plate thickness
Plate separation
Plate area
Both (b) and (c)
4680. Which resistor will be physically larger in size-
10Ω 50W
100Ω 10W
1ΜΩ 1W
1KΩ 1W