MCQOPTIONS
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MCQOPTIONS
This section includes 614 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.
| 451. |
Surface resistance of an insulating material is reduced due to the |
| A. | Smoky and dirty atmosphere |
| B. | Humidity in the atmosphere |
| C. | Both A and B |
| D. | Neither A nor B |
| Answer» D. Neither A nor B | |
| 452. |
If the resistance of a conductor does not vary in accordance with Ohm’s law it is known as |
| A. | non-linear conductor |
| B. | reverse conductor |
| C. | bad-conductor |
| D. | non-conductor |
| Answer» B. reverse conductor | |
| 453. |
In thermocouples which of the following pairs is commonly used ? |
| A. | Copper-constantan |
| B. | Aluminium-tin |
| C. | Silver-German silver |
| D. | Iron-steel |
| Answer» B. Aluminium-tin | |
| 454. |
Due to which of the following reasons aluminium does not corrode in atmosphere ? |
| A. | Aluminium is a noble metal |
| B. | Atmospheric oxygen can only diffuse very slowly through the oxide layer which is formed on the surface of aluminium |
| C. | No reaction with oxygen occurs ft Any of the above |
| D. | All of the above |
| Answer» C. No reaction with oxygen occurs ft Any of the above | |
| 455. |
Addition of 0.3 to 4.5% silicon to iron __________ the electrical resistivity of iron. |
| A. | Increases |
| B. | Decreases |
| C. | Does not change |
| D. | Change |
| Answer» B. Decreases | |
| 456. |
The carbon percentage is least in |
| A. | low carbon steel |
| B. | wrought iron |
| C. | cast iron |
| D. | malleable iron |
| Answer» C. cast iron | |
| 457. |
The transition temperature of mercury is |
| A. | 18.0°K |
| B. | 9.22°K |
| C. | 4.12°K |
| D. | 1.14’K |
| Answer» D. 1.14’K | |
| 458. |
Which of the following high resistance materials has the highest operating temperature ? |
| A. | Kanthal |
| B. | Manganin |
| C. | Nichrome |
| D. | Eureka |
| Answer» B. Manganin | |
| 459. |
Thermocouples are mainly used for the measurement of |
| A. | Temperature |
| B. | Resistance |
| C. | Eddy currents |
| D. | Coupling co-efficient |
| Answer» B. Resistance | |
| 460. |
Due to which of the following reasons copper and aluminium are not used for heating elements ? |
| A. | Both have great tendency for oxidation |
| B. | Both have low melting point |
| C. | Very large length of wires will be required |
| D. | All of the above |
| Answer» E. | |
| 461. |
In a crystal, an atom vibrates at a frequency determined by |
| A. | The heat content of the crystal |
| B. | The temperature of the crystal |
| C. | The stiffness of the bonds it makes with neighbors |
| D. | All of the above |
| Answer» D. All of the above | |
| 462. |
Platinum is used in |
| A. | Electrical contacts |
| B. | Thermocouple |
| C. | Heating element in high temperature furnace |
| D. | Grids of special purpose vacuum tubes |
| E. | All of the above |
| Answer» F. | |
| 463. |
The forbidden gap in an insulator is |
| A. | Large |
| B. | Small |
| C. | Nil |
| D. | Any of the above |
| Answer» B. Small | |
| 464. |
Which of the following materials is preferred for transmitting electrical energy over long distance ? |
| A. | Copper |
| B. | Aluminium |
| C. | Steel reinforced copper |
| D. | Steel reinforced aluminium |
| Answer» E. | |
| 465. |
Which of the following material is not a semiconductor ? |
| A. | Silica |
| B. | Germanium |
| C. | Selenium |
| D. | Gallium-arsenide |
| Answer» B. Germanium | |
| 466. |
A carbon resistor contains |
| A. | Carbon crystals |
| B. | Solid carbon granules |
| C. | Pulverized coal |
| D. | Finely divided carbon black. |
| Answer» E. | |
| 467. |
Solder is an alloy of |
| A. | Copper and aluminium |
| B. | Tin and lead |
| C. | Nickel, Copper and zinc |
| D. | Silver, copper and lead |
| Answer» C. Nickel, Copper and zinc | |
| 468. |
At transition temperature the value of critical field is |
| A. | Zero |
| B. | Negative real value |
| C. | Positive real value |
| D. | Complex value |
| Answer» B. Negative real value | |
| 469. |
Carbon electrodes are not used in |
| A. | GLS lamps |
| B. | Electric arc furnace |
| C. | Dry cells |
| D. | Cinema projectors |
| Answer» B. Electric arc furnace | |
| 470. |
The formula __________ determines the number of electrons that can be accommodated in any level. |
| A. | 2n2 |
| B. | 4n2 |
| C. | 2n3 |
| D. | 4ns |
| Answer» B. 4n2 | |
| 471. |
The covalent bond is formed by |
| A. | Transfer of electrons between atoms |
| B. | Sharing of electrons between atoms |
| C. | Sharing of variable number of electrons by a variable number of atoms |
| D. | None of the above |
| Answer» C. Sharing of variable number of electrons by a variable number of atoms | |
| 472. |
Non-linear resistors |
| A. | Produce harmonic distortion |
| B. | Follows Ohm’s law at low temperatures only |
| C. | Result in non-uniform heating |
| D. | None of the above |
| Answer» B. Follows Ohm’s law at low temperatures only | |
| 473. |
A good electric contact material should have all of the following properties except |
| A. | High resistivity |
| B. | High resistance to corrosion |
| C. | Good thermal conductivity |
| D. | High melting point |
| Answer» B. High resistance to corrosion | |
| 474. |
_________ is most commonly used for making magnetic recording tape |
| A. | Silver nitrate |
| B. | Ferric oxide |
| C. | Small particles of iron |
| D. | Silicon-iron |
| Answer» C. Small particles of iron | |
| 475. |
Overhead telephone wires are made of |
| A. | aluminium |
| B. | steel |
| C. | ACSR conductors |
| D. | Copper |
| Answer» C. ACSR conductors | |
| 476. |
The superconductivity is due to |
| A. | The crystal structure having no atomic vibration at 0°K |
| B. | All electrons interact in the super-conducting state |
| C. | The electrons jump into nucleus at 0°K |
| D. | None of the above |
| Answer» B. All electrons interact in the super-conducting state | |
| 477. |
Carbon rods are used in wet and dry cells because |
| A. | Carbon rod serves as conductor |
| B. | Carbon can resist the attack of battery acid |
| C. | Both A and B |
| D. | Either A or B |
| Answer» D. Either A or B | |
| 478. |
The photo-electric effect occurs only when the incident light has more than a certain critical |
| A. | Intensity |
| B. | Speed |
| C. | Frequency |
| D. | Wave length |
| Answer» D. Wave length | |
| 479. |
The impurity atoms is semiconductors |
| A. | Inject more charge carriers |
| B. | Reduce the energy gap |
| C. | Increase the kinetic energy of valence electrons |
| D. | All of the above |
| Answer» C. Increase the kinetic energy of valence electrons | |
| 480. |
Substances whose specific resistance abruptly decreases at very low temperature are called |
| A. | Insulators |
| B. | Conductors |
| C. | Semiconductors |
| D. | Superconductors |
| Answer» E. | |
| 481. |
For a hole which of the following statements is incorrect ? |
| A. | Holes can exist in certain semiconductors only |
| B. | Holes can exist in any material including conductors |
| C. | Holes may constitute an electric current |
| D. | Holes can be considered as a net positive charge |
| Answer» C. Holes may constitute an electric current | |
| 482. |
Carbon bearings are used under which of the following conditions ? |
| A. | Where lubrication is difficult or im-possible |
| B. | Where corrosive chemical action exists |
| C. | Where high temperature exists |
| D. | All of the above |
| Answer» E. | |
| 483. |
By increasing impurity content in the metal alloy the residual resistivity always |
| A. | Decreases |
| B. | Increases |
| C. | Remains constant |
| D. | Becomes temperature independent |
| Answer» C. Remains constant | |
| 484. |
Which of the following factors affect resistivity of metals ? |
| A. | Age hardening |
| B. | Alloying |
| C. | Temperature |
| D. | Cold work |
| E. | All of the above |
| Answer» F. | |
| 485. |
Is viscoelastic. |
| A. | Cast-iron |
| B. | Graphite |
| C. | Rubber |
| D. | Glass |
| Answer» D. Glass | |
| 486. |
The value of critical field below the transition temperature will |
| A. | Increase |
| B. | Decrease |
| C. | Remain unchanged |
| D. | Any of the above |
| Answer» B. Decrease | |
| 487. |
Which of the following variety of copper has the best conductivity ? |
| A. | Induction hardened copper |
| B. | Hard drawn copper |
| C. | Pure annealed copper |
| D. | Copper containing traces of silicon |
| Answer» D. Copper containing traces of silicon | |
| 488. |
The number of atoms per unit cell in B.C.C. structure is |
| A. | 1 |
| B. | 2 |
| C. | 4 |
| D. | 8 |
| Answer» C. 4 | |
| 489. |
The tiny block formed by the arrangement of a small group of atoms is called the |
| A. | Unit cell |
| B. | Space lattice |
| C. | Either A or B |
| D. | None of the above |
| Answer» B. Space lattice | |
| 490. |
Piezoelectric materials serve as a source of ________ . |
| A. | Resonant waves |
| B. | Musical waves |
| C. | Microwaves |
| D. | Ultrasonic waves |
| Answer» E. | |
| 491. |
On which of the following factors does the resistivity of a material depend ? |
| A. | Resistance of the conductor |
| B. | Area of the conductor section |
| C. | Length of the conductor |
| D. | All of the above |
| Answer» E. | |
| 492. |
Which of the following resistive materials has the lowest temperature co-efficient of resistance ? |
| A. | Nichrome |
| B. | Constantan |
| C. | Kanthal |
| D. | Molybdenum |
| Answer» B. Constantan | |
| 493. |
The converse of hardness is known as |
| A. | Malleability |
| B. | Toughness |
| C. | Softness |
| D. | None of the above |
| Answer» D. None of the above | |
| 494. |
In graphite, bonding is |
| A. | Covalent |
| B. | Metallic |
| C. | Vander Waals |
| D. | Vander Waals and covalent |
| Answer» E. | |
| 495. |
Superconductors are becoming popular for use in |
| A. | Generating very strong magnetic field |
| B. | Manufacture of bubble memories |
| C. | Generating electrostatic field |
| D. | Generating regions free from magnetic field |
| Answer» B. Manufacture of bubble memories | |
| 496. |
Total number of crystal systems is |
| A. | 2 |
| B. | 4 |
| C. | 7 |
| D. | 12 |
| Answer» D. 12 | |
| 497. |
Cap screws are |
| A. | similar tosmall size tap bolts except that a greater variety of shapes of heads are available |
| B. | slotted for a screw driver and generally used with a nut |
| C. | used to prevent relative motion be-tween parts |
| D. | provided with detachable caps |
| Answer» B. slotted for a screw driver and generally used with a nut | |
| 498. |
Lead is poured into the joint between two pipes. These pipes may be made of |
| A. | cast iron |
| B. | vitrified clay |
| C. | asbestos cement |
| D. | concrete |
| Answer» B. vitrified clay | |
| 499. |
The transistor is made of |
| A. | silver |
| B. | gold |
| C. | copper |
| D. | germanium |
| Answer» E. | |
| 500. |
Recrystallisation temperature can belowered by |
| A. | purification of metal |
| B. | grain refinement |
| C. | working at lower temperature |
| D. | all of the above |
| Answer» E. | |