Utilisation of electrical energy (MCQ)

1➤ In which type of heating following factors need to be considered: Thickness of the surfaces to be heated

Induction frequencyDielectric frequencyRadiant frequencyInfrared frequency

2➤ Variable speed cannot be obtained with

DC motors controller AC & DC controllersderivative controllersoft starter controller

3➤ Which is the color of light emitted by the sodium vapour lamp?

BlueYellowWhiteGreen

4➤ Why is electric braking preferred?

Because it avoids wear and tearBecause the motor continues to remain loaded during brakingBecause it is instantaneousBecause heat generated is more

5➤ Which one of the following is an example of plastic welding?

Thermit welding without pressureGas weldingArc weldingResistance welding

6➤ Series-parallel speed control method used in traction system gives a speed range of about:

1:31:21:41:5

7➤ It is required to provide an illumination of 100 lux in a factory hall of 30 m length and 15 m breadth. Assume the depreciation factor is 0.8, coefficient of utilisation is 0.4 and efficiency of lamp is 14 lumen/watt. Suggest the number of lamps required when rating of the lamp is 250 W.

801004020

8➤ Filament used in a Halogen lamp is made up of -

MagninTungstenNichromeEureka

9➤ The capacity of a battery is 60 Ah. For how long can the current of 5 ampere be drawn from this battery

7.2 hours8.5 hours300 hours12 hours

10➤ Which of the following is NOT an advantage of individual electric drive ?

Risk of accident is less.Flexibility in installationIt can be run and stopped as desired It has low initial cos

11➤ Which of the following motors is the most suitable for urban and sub urban services of electric traction?

Three phase synchronous motorThree phase Induction motorSeparately excited D. C. motor D. C. series motor

12➤ A single-phase AC arc welding transformer supplies approximately

220 volts at 0.8 power factor60 volts at 0.35 power factor 100 volts at 0.35 power factor100 volts at 0.6 power factor

13➤ In steam locomotive, electric power is provided through

Overhead wireSmall turbo generatorDiesel engine generatorBattery system

14➤ Which of the following methods of heating is not dependent on the frequency of supply?.

Electric Resistance heatingDielectric heatingInduction heatingAll of the above

15➤ Arc blow is caused by

Radio disturbanceElectrical disturbanceElectronic disturbanceMagnetic disturbance

16➤ Which of the following statement is true for DC Straight Polarity (DCSP) in welding?

Electrode is made positive and workpiece negativeElectrode is made negative and workpiece positiveBoth electrode as well as workpiece are made positiveBoth electrode as well as workpiece are made negative

17➤ Which of the following heating is used for paint drying and for drying foundary moulds?.

Infrared HeatingIndirect Resistance HeatingEddy Current HeatingDirect Arc Heating

18➤ Which of the heating methods has low lagging power factor?

Arc HeatingCoreless Induction HeatingDielectric HeatingResistance Heating

19➤ Which of the following properties is NOT related to carbon electrodes in arc furnaces?

InsolubilityResistance to thermal shockLow melting pointInertness

20➤ Which of the following materials is used as heating element in domestic appliances?

CopperBrassGINichrome

21➤ Which of the following law deals with designing of Heating Element?

Ohm's lawKirchhoff's lawFaraday's lawStefan's law

22➤ A process that converts electric energy into heat energy is known as electric heating What are some essential requirements for a good heating element? A. High specific resistance B. High melting point C. High mechanical strength D. Non-corrosive

A, B and DA, C and D A, B and CA, B, C and D

23➤ Which of the following is NOT an advantage of electric heating?

Simple and accurate pressure control can be made either by manual or fully automatic switchesThe overall efficiency of electric heating is much higherSpecial type of heating can be done very accurately by electric heating system.This system is free from dirt.

24➤ Which of the following is NOT true about Space/Height Ratio in illumination? It is ratio of horizontal distance

It used only in application of sodium vapour lampFor indoor lighting value of this ratio lies between 1 and 2It depends on the nature of the polar curve of lamp between two lamp to mounting height of lamp

25➤ Why is tungsten used in the incandescent lamp filaments?

Tungsten is an inert element in last column Group 18 periodic tableTungsten is very hard & difficult to break the thin filament 2.Tungsten is less corroding at high temperaturesTungsten has high melting point

26➤ Which of the following emit greenish-blue colour ?

Neon lampMercury vapour lampNeon tubeSodium vapour lamp

27➤ Which of the following in NOT the correct in designing a good point to be considered lightning scheme?

The size of the room.The temperature of the roomThe selection of the required lamp and fittingThe intensity of illumination required

28➤ In which of the following lighting scheme, 60 to 90% of total light flux is thrown upward to the ceiling?

General diffusing lightingIndirect lightingDirect lighting Semi-indirect lighting

29➤ Which of the following terms is related to illumination?

Mass CurvePolar Plot HydrographPolar Curve

30➤ 100 V lamp takes a current of 20 A. If the total flux is 3600 π, find the mean spherical candle-power of the lamp.

900300450750

31➤ According to Lambert's Cosine Law of Illumination, the illumination at any point on a surface is proportional to the cosine of the angle between

Normal at that point and the incident rayNormal at that point and the direction of luminous fluxNormal at that point and the direction of radiation of lightNormal at that point and the direction of reflection of light

32➤ Which of the following formula is correct for Reduction Factor (R) in illumination?

flux/areaMSCP/MHCPNone of theseBoth of these

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