Basic Electrical Engineering: Part-3 Solved Objective

OBJECTIVE QUESTIONS FROM BASIC ELECTRICAL ENGINEERING:

[1] The power plant having highest efficiency is

A.  Hydro

B.  Thermal
C.  Nuclear
D.  Diesel

Ans:C

[2] As the spacing between plates in a capacitor is made smaller

A.  The capacitance increases

B.  The capacitance decreases

C.  The capacitance does not change

D.  The resistance increases

Ans: A

[3] The relationship between frequency and time period of ac waveform is
A.  f = T
B.  f = 1/ T²
C.  f = 1/T
D.  f = T²

Ans:C

[4] The five 0.050uF capacitors are connected in parallel. The equivalent capacitance is

A.  0.010 uf

B.  0.25 uf

C.  0.50uf

D.  0.025uf

Ans: B

[5] The current gain of a bipolar transistor drops at high frequencies because of

A. Transistor capacitance

B. High current effects in the base

C. Parasitic inductive elements

D. The early effect

Ans:A

[6] If two perfect sine waves have the same frequency and the same amplitude, but are in opposite phase, the composite wave
A.  Has twice the amplitude of either input wave alone

B.  Has half the amplitude of either input wave alone

C.  Is complex, but has the same frequency as the originals.

D.  Has zero amplitude ( that is, it does not exist) because the two input waves cancel each other out.

Ans: D

[7] Three capacitors are connected in series having capacitance of 8uF, 32uF, 16uF, the total capacitance is

A. 32/7 uF

B. 7.32 uF

C. 56 uF

D. 32 uF

Ans:A

[8] Which one of the following does not affect the power output available from a particular ac generator?

A.  The strength of the magnet

B.  The number of turns in the coil

C.  The type of natural energy source used

D.  The speed of rotation of the coil or magnet

Ans:C

[9] Which of the following are active components

(a) Resistor and inductor

(b) Diode, BJT, FET

(c) Opamp, BJT, thermionic triode

(d) Capacitor, Inductor

Ans: B

[10] The energy required to charge a 10 uF capacitor to 100V is 

(a) 0.10 J

(b) 0.05 J

(c) 5 X 10-9 J

(d) 10 X 10-9 J

Ans: B

[11] The current in a inductor changes from 0 to 200mA in 4ms and induces a voltage of 100mV. The value of inductor is

(a) 2mH

(b) 0.5mH

(c) 8mH

(d) 4mH

Ans: A

[12] A battery has a short-circuit current of 30A and an open circuit voltage of 24V. If the battery is connected to an electric bulb of resistance 2 ?, the power dissipated by the bulb is

(a) 80W

(b) 1800W

(c) 112.5W

(d) 228W

Ans: C

[13] Which of the following is ferromagnetic material?

(a)  Copper

(b)  Palladium

(c)  Silver

(d)  Cobalt

Ans:D

[14] A complex wave form made up frequency components 1 Hz, 3 Hz, 5 Hz, 7 Hz and 9 Hz. Its fundamental frequency is

(a)  9 Hz

(b)  12.5 Hz

(c)  1 Hz

(d)  Indeterminate

Ans: 1 Hz

[15] If a 175V dc source were connected in series with the utility mains from a standard wall outlet, the result would be

(a)  Smooth dc at a constant voltage

(b)  Pure ac with equal peak voltages

(c)  Ac with one peak voltage greater than the other

(d)  Fluctuating dc

Ans:D