The value of the directional derivative of the function 𝛷(𝑥, 𝑦, 𝑧) = 𝑥𝑦2 + 𝑦𝑧2 + 𝑧𝑥2

The value of the directional derivative of the function 𝛷(𝑥, 𝑦, 𝑧) = 𝑥𝑦2 + 𝑦𝑧2 + 𝑧𝑥2

Q. The value of the directional derivative of the function 𝛷(𝑥, 𝑦, 𝑧) = 𝑥𝑦2 + 𝑦𝑧2 + 𝑧𝑥2 at the point (2, -1, 1) in the direction of the vector 𝐩 = 𝐢 + 2𝐣 + 2𝐤 is (A) 1                           (B) 0.95                      (C) 0.93                      (D) 0.9 Ans: 1 Sol:

The value of the directional derivative of the function 𝛷(𝑥, 𝑦, 𝑧) = 𝑥𝑦2 + 𝑦𝑧2 + 𝑧𝑥2 Read More »

In the figure, the voltages are 𝑣1(𝑡) = 100cos(𝜔𝑡), 𝑣2(𝑡) = 100cos

In the figure, the voltages are 𝑣1(𝑡) = 100cos(𝜔𝑡), 𝑣2(𝑡) = 100cos

Q. In the figure, the voltages are 𝑣1(𝑡) = 100cos(𝜔𝑡), 𝑣2(𝑡) = 100cos(𝜔𝑡 + 𝜋/18) and 𝑣3(𝑡) = 100cos(𝜔𝑡 + 𝜋/36). The circuit is in sinusoidal steady state, and 𝑅 << 𝜔𝐿. 𝑃1, 𝑃2 and 𝑃3 are the average power outputs. Which one of the following statements is true? (A) 𝑃1 = 𝑃2 = 𝑃3

In the figure, the voltages are 𝑣1(𝑡) = 100cos(𝜔𝑡), 𝑣2(𝑡) = 100cos Read More »

Two wattmeter method is used for measurement of power in a balanced three-phase load supplied

Two wattmeter method is used for measurement of power in a balanced three-phase load supplied

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

Two wattmeter method is used for measurement of power in a balanced three-phase load supplied Read More »

In a salient pole synchronous motor, the developed reluctance torque attains the maximum value when the load

In a salient pole synchronous motor, the developed reluctance torque attains the maximum value when the load

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°

In a salient pole synchronous motor, the developed reluctance torque attains the maximum value when the load Read More »

A single-phase 100 kVA, 1000 V / 100 V, 50 Hz transformer has a voltage drop of 5% across its

A single-phase 100 kVA, 1000 V / 100 V, 50 Hz transformer has a voltage drop of 5% across its

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)

A single-phase 100 kVA, 1000 V / 100 V, 50 Hz transformer has a voltage drop of 5% across its Read More »

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