Tuesday, February 9, 2016

Electrical Engineering Basics Objective Questions with Answers: Part-17

Electrical Engineering Basics Objective Questions with Answers

[1] Electrostatics is a branch of electricity concerned with
(a) Energy flowing across a gap between conductors
(b) Charges at rest
(c) Charges in motion
(d) Energy in the form of charges


[2] Four 2 μF capacitors are connected in series. The equivalent capacitance is
(a) 8 μF
(b) 0.5 μF
(c) 2 μF
(d) 6 μF


[3] State which of the following is false.
The capacitance of a capacitor
(a) Is proportional to the cross-sectional area of the plates
(b) Is proportional to the distance between the plates
(c) Depends on the number of plates
(d) Is proportional to the relative permittivity of the dielectric


[4] The capacitance of a capacitor is the ratio
(a) Charge to potential difference between plates
(b) Potential difference between plates to plate spacing
(c) Potential difference between plates to thickness of dielectric
(d) Potential difference between plates to charge


[5] Which of the following statement is false?
(a) An air capacitor is normally a variable type
(b) A paper capacitor generally has a shorter service life than most other types of
capacitor
(c) An electrolytic capacitor must be used only on a.c. supplies
(d) Plastic capacitors generally operate satisfactorily under conditions of high temperature


[6] The potential difference across a 10 μF capacitor to charge it with 10mC is
(a) 10V
(b) 1 kV
(c) 1V
(d) 10V


[7] The energy stored in a 10μF capacitor when charged to 500V is
(a) 1.25 mJ
(b) 0.025 μJ
(c) 1.25 J
(d) 1.25 C


[8] The capacitance of a variable air capacitor is at maximum when
(a) The movable plates half overlap the fixed plates
(b) The movable plates are most widely separated from the fixed plates
(c) Both sets of plates are exactly meshed
(d) The movable plates are closer to one side of the fixed plate than to the other


[9] The unit of magnetic flux density is the:
(a) Weber
(b) Weber per metre
(c) Ampere per metre
(d) Tesla


[10] The charge on a 10 pF capacitor when the voltage applied to it is 10 kV is
(a) 100 μC
(b) 0.1 C
(c) 0.1 μC
(d) 0.01 μC


[11] Four 2 μF capacitors are connected in parallel. The equivalent capacitance is
(a) 8 μF
(b) 0.5 μF
(c) 2 μF
(d) 6 μF


[12] In a series a.c. circuit the voltage across a pure inductance is 12V and the voltage across a pure resistance is 5V. The supply voltage is
(a) 13V
(b) 17V
(c) 7V
(d) 2.4V


[13] Inductive reactance results in a current that
(a) Leads the voltage by 90deg
(b) Is in phase with the voltage
(c) Leads the voltage by π rad
(d) Lags the voltage by π/2 rad


[14] A 10Ω resistor is connected in parallel with a 15 Ω resistor and the combination in series with a 12 Ω resistor. The equivalent resistance of the circuit is:
(a) 37Ω
(b) 18 Ω
(c) 27 Ω
(d) 4 Ω


[15] The equivalent resistance when a resistor of (1/3)Ω is connected in parallel with a (1/4)Ω resistance is:
(a) 1/7 Ω
(b) 7Ω
(c) 1/12 Ω
(d) 3/4 Ω

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7:56 AM