Users Also Read

MCQ's Search Engine

Electrical Engineering

Mechanical Engineering

Civil Engineering

Automobile Engineering

Chemical Engineering

Computer Engineering

Electronics Engineering

Medical Science Engg

Q1. | Which of the following statements pertains to resistors only? |

A. | They oppose sudden changes in voltages. [Wrong Answer] |

B. | They can act as energy storage devices. [Wrong Answer] |

C. | They can dissipate desirable amount of power. [Correct Answer] |

D. | None of the above [Wrong Answer] |

View Answer
Explanation:-
Answer : CDiscuss it below :!! OOPS Login [Click here] is required to post your answer/resultHelp other students, write article, leave your comments |

**Also Read Similar Questions Below :**

⇒ ''Cogging'' in induction motor occurs when

number of stator teeth - number of rotor teeth = odd number.

number of stator teeth - number of rotor teeth = even number.

number of stator teeth - number of rotor teeth = 0.

number of stator teeth - number of rotor teeth = negative number.

⇒ Which of the following 3-phase connections of a transformer causes interference to the nearby communication systems?

Delta-star.

Star-delta.

Star-star.

Delta-delta.

⇒ In a single phase induction motor driving a fan load, the reason for having a high resistance rotor is to achieve

low starting torque.

quick acceleration.

high efficiency.

reduced size.

⇒ In an induction motor, if the air gap is increased

speed will reduce.

efficiency will improve

power factor will he lowered

breakdown torque will reduce

⇒ The capacitor start motor like resistance start motor, has the auxiliary winding disconnected by means of a centrifugal switch as the motor picks up speed. This is necessary because

the capacitance that gives the largest starting torque is about four tïmes too big for the best running conditions

if the capacitor is used only for starting, it can be electrolytic type which is much smaller and cheaper than the paper capacitor required for continuous operation.

both (a) and (b).

none of these.

⇒ Two series motors are mechanically coupled. One machine is running as a motor and the other as a generator. The iron and friction losses of the machines will be identical when

their speeds are identical.

their speeds and excitations are identical.

their speeds are equal but back emfs are half the supply voltages.

their ratings and armature sizes are identical.

⇒ In a power transformer, if in place of sinusoidal wave, a peaked wave voltage is fed to the primary

copper losses will be less.

noise level will be reduced.

iron losses will be more.

iron losses will be less.

⇒ The terminal voltage of an overcompounded dc generator

decreases with the increase in load current.

increases with the increase in load current.

remains constant at all load currents.

none of the above.

⇒ Which of the following motors is suitable for timing and control purposes?

Reluctance motor

Series motor

Repulsion motor

Hysteresis motor

⇒ What is the core loss in a high frequency ferrite core transformer used in SMPS power supply?

10% of rated power.

5% of rated power.

2% of rated power.

1% of rated power.

⇒ Which of the following is a vector quantity?

Standing wave ratio only.

Reflection coefficient only.

Gain.

Standing wave ratio and reflection coefficient.

⇒ The no-load current in an induction motor is in comparison to that of a power transformer.

much lower

much higher

slightly less

slightly more

⇒ The two windings of a transformer are

conductively linked.

inductively linked.

not linked at all.

electrically linked.

⇒ The torque-slip characteristic of an induction motor is approximately a/an

straight line.

rectangular parabola.

parabola.

hyperbola.

⇒ In various types of split-phase l-phase induction motors, the starting torques produced are in the following descending order

Capacitor-split, resistor-split, shaded pole.

Capacitor-split, shaded-pole, resistor split.

Resistor-split, capacitor-split, shaded pole.

Shaded pole, resistor-split, capacitor-split.

⇒ Which one of the following statements is not correct in respect of synchronous machines?

In salient pole machines, the direct-axis synchronous reactance is greater than the quadrature axis synchronous reactance.

The damper bars help the motor to self start.

Short-circuit ratio is the ratio of field current required to produce the rated voltage on open circuit to the rated armature current.

The V - curve of a synchronous motor represents the variation in armature current with field excitation at a given output power.

⇒ A dc motor develops the maximum mechanical power when the armature current is such that

the back ernf is equal to 3/4th of the applied emf.

the back emf is equal to one-half of the applied emf.

the back emf is equal to 1/4th of the applied emf.

the back emf is equal to 2/3rd of the applied emf.

⇒ 1f a single phase motor fails to start, it may be due to

blown fuses

open-circuit in auxiliary winding

open-circuit in main winding

any of the above causes

⇒ For nonreversing dc drives it is preferable to use

plugging.

regenerative braking.

dynamic braking with separate excitation.

dynamic braking with self excitation.

⇒ Which part of transformer is subjected to maximum heating?

Frame.

Core.

Winding.

Oil.

⇒ The excessive temperature rise will cause maximum damage to

winding insulation.

core laminations.

copper windings.

dielectric strength of oil.

⇒ The unit of the Poynting vector is

power.

power density.

energy.

energy density.

⇒ Which one of the following statements is correct?

Both Laplance's and Poisson's equations are nonlinear equations.

Laplance's equation is nonlinear but Poisson's equation is linear.

Laplace' s equation is linear but Poisson's equation is nonlinear.

Both Laplace's and Poisson's equations are linear.

⇒ The synchronous speed for the seventh space harmonic mmf wave of a 3-phase. 8-pole, 50 Hz induction machine is

107.14 rpm in forward direction.

107.14 rpm in reverse direction.

5.250 rpm in forward direction.

5.250 rpm in ieverse direction.

⇒ The armature mmf of a dc machine has

triangular space distribution and rotates at the speed of armature.

trapezoidal space distribution and is stationary in space

stepped distribution and rotates at the speed of armature

triangular space distribution and is stationary in space

⇒ A balanced 3-phase induction motor runs at slip s. If is its synchronous speed, what is the relative speed between the stator mmf and rotor mmf?

sω

(1 - s)ω

ω

zero

⇒ Consider the following statements:

The armature torque in a dc motor is a function of

1. Field flux

2. Armature current

3. Speed

4. Damping

Which of the above statements is/are correct?

1,2,3 and 4.

3 and 4 only.

1 and 2 only.

4 only.

⇒ In a Ward-Leonard drive, if the field current of the dc generator is suddenly reduced, the controlled de motor operates

still in the motoring mode.

in dynamic braking mode.

in counter-current braking mode.

in regenerative braking mode.

⇒ A repulsion motor is equipped with

slip rings.

centrifugal switch.

commutators and brushes.

all of the above.

⇒ In an RLC series resonant circuit, if the maximum stored energy is increased by 10% and at the same time the energy dissipated per cycle is reduced by 10%, it will result in which one of the following?

An 11% decrease in quality factor.

An increase in the resonant frequency by 11%.

A 22% increase in quality factor.

A decrease in the resonant frequency by 22%.