MCQOPTIONS
Saved Bookmarks
MCQOPTIONS
This section includes 991 Mcqs, each offering curated multiple-choice questions to sharpen your GATE (Mechanical Engineering) knowledge and support exam preparation. Choose a topic below to get started.
| 851. |
In a vibrating reed frequency meter the natural frequencies of two adjacent reeds have a difference of |
| A. | 0.1 Hz |
| B. | 0.25 Hz |
| C. | 0.5 Hz |
| D. | 1.5 Hz |
| Answer» D. 1.5 Hz | |
| 852. |
_______ is extensively used for those portions of magnetic circuit which carry steady flux and need superior mechanical properties ? |
| A. | Grey cast-iron |
| B. | Cast steel |
| C. | High carbon steel |
| D. | Stainless steel |
| Answer» C. High carbon steel | |
| 853. |
A phase shifting transformer is used in conjunction with |
| A. | D.C. potentiometer |
| B. | Drysdale potentiometer |
| C. | co-ordinate potentiometer |
| D. | Crompton potentiometer |
| Answer» C. co-ordinate potentiometer | |
| 854. |
The function of shunt in an ammeter is to |
| A. | by pass the current |
| B. | increase the sensitivity of the ammeter |
| C. | increase the resistance of ammeter |
| D. | none of the above |
| Answer» B. increase the sensitivity of the ammeter | |
| 855. |
The voltage control in electric supply networks in required on account of which of the following reasons ? |
| A. | Adjustment of voltage at consumers premises within statutory limits |
| B. | Control of active and reactive power |
| C. | Adjustment of short period daily and seasonal voltage variations in accordance with variations of load |
| D. | All of the above |
| Answer» E. | |
| 856. |
The value of exciting or magnetizing current depends upon which of the following factors ? |
| A. | Total m.m.f. required |
| B. | The number of turns in the exciting winding |
| C. | The way in which the winding is distributed |
| D. | All of the above |
| Answer» E. | |
| 857. |
An instrument transformer is used to extend the range of |
| A. | induction instrument |
| B. | electrostatic instrument |
| C. | moving coil instrument |
| D. | any of the above |
| Answer» B. electrostatic instrument | |
| 858. |
An induction meter can handle current up to |
| A. | 10 A |
| B. | 30 A |
| C. | 60 A |
| D. | 100 A |
| Answer» E. | |
| 859. |
In transformers using hot rolled steel, the cross-section of the yoke is made about _____ greater than that of the core |
| A. | 5 percent |
| B. | 10 percent |
| C. | 15 percent |
| D. | 30 percent |
| E. | none of the above |
| Answer» D. 30 percent | |
| 860. |
Which of the following properties a damping oil must possess ? |
| A. | Must be a good insulator |
| B. | Should be non-evaporating |
| C. | Should not have corrosive action upon the metal of the vane |
| D. | The viscosity of the oil should not change with the temperature |
| E. | All of the above |
| Answer» F. | |
| 861. |
The action of electromagnetic machines can be related to which of the following basic principles ? |
| A. | Induction |
| B. | Interaction |
| C. | Alignment |
| D. | All of the above |
| Answer» E. | |
| 862. |
The heated parts of an electrical machine dissipate heat into their surroundings by which of the followingmodes of heat dissipation ? |
| A. | Conduction |
| B. | Convection |
| C. | Radiation |
| D. | All of the above |
| Answer» E. | |
| 863. |
Which of the following methods may be adopted to reduce the effects of armature reaction? |
| A. | Increase in length of air gap at pole tips |
| B. | Increasing reluctance of pole tips |
| C. | Compensating windings |
| D. | All of the above |
| Answer» E. | |
| 864. |
When the two coil sides forming a coil are spaced exactly one pole pitch apart they are said to be of |
| A. | short pitch |
| B. | full pitch |
| C. | either of the above |
| D. | none of the above |
| Answer» C. either of the above | |
| 865. |
A potentiometer may be used for |
| A. | measurement of resistance |
| B. | measurement of current |
| C. | calibration of ammeter |
| D. | calibration of voltmeter |
| E. | all of the above |
| Answer» F. | |
| 866. |
Basically a potentiometer is a device for |
| A. | comparing two voltages |
| B. | measuring a current |
| C. | comparing two currents |
| D. | measuring a voltage |
| E. | none of the above |
| Answer» B. measuring a current | |
| 867. |
An induction wattmeter can be used for |
| A. | both D.C. and A.C. |
| B. | D.C. only |
| C. | A.C. only |
| D. | any of the above |
| Answer» D. any of the above | |
| 868. |
A dynamometer wattmeter can be used for |
| A. | both D.C. and A.C. |
| B. | D.C. only |
| C. | A.C. only |
| D. | any of the above |
| Answer» B. D.C. only | |
| 869. |
Standard resistor is made from |
| A. | platinum |
| B. | maganin |
| C. | silver |
| D. | nichrome |
| Answer» C. silver | |
| 870. |
Two holes in the disc of energy meter are drilled at the opposite sides of the spindle to |
| A. | improve its ventilation |
| B. | eliminate creeping at no load |
| C. | increase its deflecting torque |
| D. | increase its braking torque |
| Answer» C. increase its deflecting torque | |
| 871. |
Which of the following materials is used in the manufacture of resistance grids to be used in the starters of largemotors ? |
| A. | Copper |
| B. | Aluminium |
| C. | Steel |
| D. | Cast-iron |
| Answer» E. | |
| 872. |
If an insulating material is operated beyond the maximum allowable temperature, its life is |
| A. | drastically increased |
| B. | drastically reduced |
| C. | unaffected |
| D. | none of the above |
| Answer» C. unaffected | |
| 873. |
In D.C. machines the number of slots per pole usually lies |
| A. | between 2 to 4 |
| B. | between 6 to 8 |
| C. | between 9 to 16 |
| D. | between 20 to 30 |
| Answer» D. between 20 to 30 | |
| 874. |
In order to achieve high accuracy, the slide wire of a potentiometer should be |
| A. | as long as possible |
| B. | as short as possible |
| C. | neither too small not too large |
| D. | very thick |
| Answer» B. as short as possible | |
| 875. |
Instrument transformers are |
| A. | potential transformers |
| B. | current transformers |
| C. | both (A) and (B) |
| D. | power transformers |
| Answer» D. power transformers | |
| 876. |
The rectifier instrument is not free from |
| A. | temperature error |
| B. | wave shape error |
| C. | frequency error |
| D. | all of the above |
| Answer» D. all of the above | |
| 877. |
For large power transformers, self oil cooled type or air blast type which of the following values of current density may be used? |
| A. | 1.0 to 1.2 A/mm² |
| B. | 1.5 to 2.0 A/mm² |
| C. | 2.2 to 3.2 A/mm² |
| D. | 3.2 to 4.2 A/mm² |
| Answer» D. 3.2 to 4.2 A/mm² | |
| 878. |
Various adjustments in an energy meter include |
| A. | light load or friction |
| B. | lag and creep |
| C. | overload and voltage compensation |
| D. | temperature compensation |
| E. | all of the above |
| Answer» F. | |
| 879. |
In D.C. machines, ir order to prevent excessive distortion of field form by the armature reaction, the field mmf must be made |
| A. | equal to that of armature mmf |
| B. | less in comparison with the armature mmf |
| C. | large in comparison with the armature mmf |
| D. | none of the above |
| Answer» D. none of the above | |
| 880. |
The electrical power to a meggar is provided by |
| A. | battery |
| B. | permanent magnet D.C. generator |
| C. | A.C. generator |
| D. | any of the above |
| Answer» C. A.C. generator | |
| 881. |
The usual values of maximum flux densities for distribution transformers using hot rolled silicon steel are |
| A. | 0.5 to 0.8 Wb/m² |
| B. | 0.8 to 1.0 Wb/m² |
| C. | 1.1 to 1.35 Wb/m² |
| D. | 1.4 to 1.8 Wb/m² |
| Answer» D. 1.4 to 1.8 Wb/m² | |
| 882. |
Commercial available medium size machines have a speed range of ______ . |
| A. | 200 to 400 r.p.m. |
| B. | 600 to 1000 r.p.m. |
| C. | 1000 to 1500 r.p.m. |
| D. | 2000 to 2500 r.p.m. |
| Answer» E. | |
| 883. |
Power transformers should be designed to have maximum efficiency |
| A. | at one-fourth load |
| B. | at one-half load |
| C. | at or near full load |
| D. | any of the above |
| Answer» D. any of the above | |
| 884. |
The cold rolled grain oriented steel has ______ permeability in the direction of the grain orientation. |
| A. | minimum |
| B. | maximum |
| C. | nil |
| D. | none of the above |
| Answer» C. nil | |
| 885. |
To measure radio frequency, the suitable frequency meter is |
| A. | Weston frequency meter |
| B. | reed vibrator frequency meter |
| C. | heterodoxy frequency meter |
| D. | electrical resonance frequency meter |
| Answer» D. electrical resonance frequency meter | |
| 886. |
Induction type single phase energy meters measure electric energy in |
| A. | kW |
| B. | Wh |
| C. | kWh |
| D. | VAR |
| E. | None of the above |
| Answer» D. VAR | |
| 887. |
In a Schering bridge the potential of the detector above earth potential is |
| A. | a few volts only |
| B. | 1 kV |
| C. | 5 kV |
| D. | 10 kV |
| Answer» B. 1 kV | |
| 888. |
is usually used for brush rockers |
| A. | Mild steel |
| B. | Copper |
| C. | Aluminium |
| D. | Cast-iron |
| Answer» E. | |
| 889. |
In ______ machines, the size of the shaft is decided by the critical speed which depends on the deflection of the shaft. |
| A. | small |
| B. | medium |
| C. | large |
| D. | any of the above |
| Answer» D. any of the above | |
| 890. |
A moving-coil permanent-magnet instrument can be used as flux meter |
| A. | by using a low resistance shunt |
| B. | by using a high series resistance |
| C. | by eliminating the control springs |
| D. | by making control springs of large moment of inertia |
| Answer» D. by making control springs of large moment of inertia | |
| 891. |
For measurements on high voltage capacitors, the suitable bridge is |
| A. | Wein bridge |
| B. | Schering bridge |
| C. | Any of the above |
| D. | None of the above |
| Answer» D. None of the above | |
| 892. |
are used for construction of core of electromagnets. |
| A. | Soft magnetic materials |
| B. | Hard magnetic materials |
| C. | Either (A) or (B) |
| D. | None of the above |
| Answer» B. Hard magnetic materials | |
| 893. |
Which of the following methods does not take into account the maximum temperature rise under variable loadconditions ? |
| A. | Equivalent power method |
| B. | Equivalent current method |
| C. | Method of average losses |
| D. | Equivalent torque method |
| Answer» D. Equivalent torque method | |
| 894. |
In induction motors, the length of air gap in kept as small as mechanically possible is order to have |
| A. | low power factor |
| B. | high power factor |
| C. | high over load capacity |
| D. | any of the above |
| Answer» C. high over load capacity | |
| 895. |
With direct water cooling it is possible to have ratings of about |
| A. | 200 MW |
| B. | 300 MW |
| C. | 400 MW |
| D. | 600 MW |
| Answer» E. | |
| 896. |
The time taken by the machine to attain 0.632 of its final steady temperature rise is called |
| A. | heating time constant |
| B. | cooling time constant |
| C. | either (A) or (B) |
| D. | none of the above |
| Answer» B. cooling time constant | |
| 897. |
In a Weston synchronoscope, the fixed coils are connected across |
| A. | bus-bars |
| B. | incoming alternator |
| C. | a lamp |
| D. | none of the above |
| Answer» C. a lamp | |
| 898. |
________ cooling is the process of dissipating the armature and field winding losses to a cooling medium circulating within the winding insulation wall |
| A. | Direct |
| B. | Indirect |
| C. | Conventional |
| D. | Any of the above |
| Answer» B. Indirect | |
| 899. |
For 275 kV transformers, using cold rolled grain oriented steel, which of the following values of flux density may be used? |
| A. | 1.0 Wb/m² |
| B. | 1.1 Wb/m² |
| C. | 1.3 Wb/m² |
| D. | 1.6 Wb/m² |
| E. | None of the above |
| Answer» E. None of the above | |
| 900. |
The disc of an instrument using eddy current damping should be of |
| A. | conducting and magnetic material |
| B. | non-conducting and magnetic material |
| C. | conducting and non-magnetic material |
| D. | none of the above |
| Answer» D. none of the above | |