Basic Electrical Engineering Interview Question Part 8

[1] For a pulse transformer, the material used for its core and the possible turn ratio from primay to secondary are respectively
(a) ferrite; 20:1
(b) laminated iron; 1:1
(c) ferrite; 1:1
(d) powdered iron; 1:1
Ans: C

[2] At the exact moment a 60Hz ac sine wave is at its positive peak voltage, the instantaneous rate of change in the voltage is
a) Large and positive
b) Small and negative
c) Large and negative
d) Small and negative
e) Zero
Ans: E

[3] The peak voltage in an ac wave is always
A. Greater than the average voltage
B. Less than the average voltage
C. Greater than or equal to average voltage
D. Less than or equal to the average voltage
Ans: C

[4] If four resistors are connected in series, each with a value of 4Kohm, the total resistance is
(a) 1kΩ
(b) 4 kΩ
(c) 8 kΩ
(d) 16 kΩ
Ans: D

[5] Consider the following statements:  [IES2010]
Piezoelectric materials serve as
1. A source of ultrasonic waves
2. When electric field is applied, the mechanical dimensions of the substances are not at all altered.
3. Converts electrical energy to mechanical and vice versa
4. Converts thermal energy to electrical energy

Which of the above statements is/are correct?
A. 1 only
B. 2 and 3 only
C. 1 and 3 only
D. 1,2,3 and 4
Answer: C

[7] The demand factor for the electrical system is the ratio of
A. Maximum demand to connected load
B. Maximum demand to average load
C. Average power to maximum power
D. Relative power to total power
Answer: A

[8] All sine waves
(a)  Have similar general appearance
(b)  Have instantaneous rise and fall times
(c)  Are in the same phase as cosine waves
(d)  Rise instantly, but decay slowly
Answer: A

[9] Suppose that two ac waves have the same frequency but differ in phase by exactly 1/20 of a cycle. What is the phase difference between these two waves?
A.  18°
B.  20°
C.  36°
D.  5.73°
Ans: A

[10] The power drawn by the circuit whose input is 20KVA and p.f is 0.8 lagging
(a) 12
(b) 20
(c) 16
(d) 8
Ans: C

[11] Watt hour is the unit of
A. Electric power
B. Electric capacity
C. Electric energy
D. Electric charge
Ans:C

[12] 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

[13] Which of the following is a polarized capacitor?
A.  Paper
B.  Mica
C.  Inter electrode
D.  Electrolytic
Ans:D

[14] If all other factors are kept constant, the inductance of the air-core coil is not affected by
A.  The frequency
B.  The number of turns
C.  The diameter of the coil
D.  The length of the coil
Ans: A