Q. Two wattmeter method is used for measurement of power in a balanced three-phase load supplied from a balanced three-phase system. If one of the wattmeters reads half of the other (both positive), then the power factor of the load is (A) 0.532 (B) 0.632 (C) 0.707 (D) 0.866 Ans: 0.866 Sol: In two Wattmeter […]
Q. Four power semiconductor devices are shown in the figure along with their relevant terminals. The device(s) that can carry dc current continuously in the direction shown when gated appropriately is (are) A. Triac only B. Triac and MOSFET C. Triac and GTO D. Thyristor and Triac Ans: Triac and MOSFET
Q. A single phase fully controlled rectifier is supplying a load with an anti-parallel diode as shown in the figure. All switches and diodes are ideal. Which one of the following is true for instantaneous load voltage and current? Ans:
Q. In a salient pole synchronous motor, the developed reluctance torque attains the maximum value when the load angle in electrical degrees is (A) 0 (B) 45 (C) 60 (D) 90 Ans: 45°
Q. A single-phase 100 kVA, 1000 V / 100 V, 50 Hz transformer has a voltage drop of 5% across its series impedance at full load. Of this, 3% is due to resistance. The percentage regulation of the transformer at full load with 0.8 lagging power factor is (A) 4.8 (B) 6.8 (C) 8.8 (D)
Q. P, Q, R and S crossed a lake in a boat that can hold a maximum of two persons, with only one set of oars. The following additional facts are available. i. The boat held two persons on each of the three forward trips across the lake and one person on each of the
Q. A designer uses marbles of four different colours for his designs. The cost of each marble is the same, irrespective of the colour. The table below shows the percentage of marbles of each colour used in the current design. The cost of each marble increased by 25%. Therefore, the designer decided to reduce equal
Q. A class of twelve children has two more boys than girls. A group of three children are randomly picked from this class to accompany the teacher on a field trip. What is the probability that the group accompanying the teacher contains more girls than boys? Ans: Option B Sol: ∵B=G+2 and B+G=12 ⇒ B=7,
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Q. In a certain code, AMCF is written as EQGJ and NKUF is written as ROYJ. How will DHLP be written in that code? (A) RSTN (B) TLPH (C) HLPT (D) XSVR Ans: HLPT
Q. An e-mail password must contain three characters. The password has to contain one numeral from 0 to 9, one upper case and one lower case character from the English alphabet. How many distinct passwords are possible? (A) 6,760 (B) 13,520 (C) 40,560 (D) 1,05,456 Ans: 40,560
