Skin effect is best defined as: The tendency of alternating current to concentrate at the center of a conductor The tendency of direct current to concentrate at the center of a conductor The tendency of alternating current to concentrate near the surface of a conductor The tendency of direct current to concentrate near the surface … Read more
Corona in transmission lines is affected by: Spacing of conductors Atmospheric conditions Voltage level Size of conductors All of these Correct answer: 5. All of these Explanation: Corona in transmission lines depends on all of the above mentioned factors: Spacing between conductors: The larger distance between conductors reduces the electrostatic stress at conductors surface Atmospheric … Read more
The most economical power factor for a consumer is: 0.84 lagging 0.9 lagging 0.95 lagging 1 (unity) Correct answer: 3. 0.95 Explanation: If a consumer improves power factor, the cost of maximum kVA demand decrease and he will have savings over his bill. However, power factor improvement requires a lot of capital investment, as well … Read more
The number of brushes in Lap Winding of DC Machines equals: Half of number of poles To the Number of poles Twice as number of pole None of these Correct answer: 2. To the Number of poles Explanation: For requiring number of P current paths there should be number of brushes that are equal to … Read more
Specific resistivity of a material depends on: Its composition Its dimensions Its resistance None of these Correct answer: 1. Its composition Explanation: The specific resistivity of a material depends on its composition
Formula for Ohm’s law field theory can be written in the form of equation: P = VI V = IR J = σE σ = JE Correct answer: 3. J = σE Ohm’s law in field theory form can be mathematically expressed as follows: J = σE where J = Current density at a given … Read more
Impedance of AC circuit is: Scalar Quantity Vector Quantity None of these Correct answer: 2. Vector quantity
The Motor which speeds up with the increase in load: Series DC Motor Shunt DC Motor Differentially compounded DC Motor Commutatively compounded DC Motor Correct answer: 3. Differentially compounded DC Motor
A 220 V DC motor having armature resistance of 0.7 Ω and back emf of 190 V will draw current: 36.92 A 42.85 A 53.64 A 68.55 A Correct answer: 2. 42.85 A Explanation: Current drawn = (V – Eb)/R = (220 – 190) / 0.7 Ω = 42.85 A So a 220 V DC … Read more
The type of DC Motor whose speed is practically constant: Series DC Motor Shunt DC Motor Commutatively compounded motor Differentially compounded Correct answer: 2. Shunt DC Motor Shunt DC motor is the type of DC Motor whose speed is practically constant