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Transcript
MCQ – Basic Electrical – Set I 1. The ratio of voltage and electric current in a closed circuit remains constant varies increases falls 2. The curve representing ohm’s law is sine function Linear A parabola a hyperbola 3. The resistance of a conductor having length l area of cross section a and resistivity ρ is given as: ρa/l ρl/a ρla l/ρa 4. The resistance of wire varies inversely as area of cross section length resistivity temperature 5. Which of the following quantities are same in all parts of a series circuit? voltage power current resistance 6.Which of the following statements is false in case of a series circuit? the voltage drop across each resister is same the current flowing through each resistor is the same applied voltage is equal to the sum of voltage drops across individual resistors resistors are additive 7. A resistance of 30 Ω is connected across 240v supply. If a resistance R Ω is connected in parallel with 30Ω resistor across the same supply, the current drawn becomes triple of original one. The unknown resistor R is 15Ω 10Ω 5Ω 30Ω 8. Three resistors, each of R ohms, are connected to form a triangle. The resistance between any two terminals will be: 2/3 R 3/2R R 3R 9. Which of the following is not correct? P=V/R^2 P=VI I=√(P/R) V=√PR 10. A 100W bulb is connected in series with a room heater. If now 100W bulb is replaced by a 40w bulb, the heater output will : increase decrease Remain the same MCQ – Basic Electrical – Set II 1. The voltage applied across an electric iron is halved. The power consumption of the iron will be: one-half three-fourth one-fourth 1/√2times 2. Resistance of 200w,250v lamp will be 625 Ω 1250Ω 312.5Ω 31.25Ω 3. Two heaters rated at 1000w, 250v each are connected in series across a 250v, 50Hz ac supply. The total power drawn from the supply will be: 1000w 500w 250w 2000w 4. A 200w, 100v lamp is to be operated on 250v supply. The additional resistance required to be connected in series will be: 125Ω 50Ω 75Ω 25Ω 5. Kirchoff’s laws are valid for linear circuits only passive time invariant circuits non-linear circuits only both linear and non-linear circuits 6. KCL is applicable only to electric circuits electronic circuits junctions in a network closed loop in a network 7. KVL is concerned with IR drop battery emf junction node both a and b 8. A wye arrangement of resistances has each resistance of 3Ω, the equivalent delta arrangement will have each resistance of values. 9Ω 6Ω 3Ω 1Ω 9. If Q.8 resistor are connected in delta arrangement then the equivalent wye will be 1Ω. 10. A battery is connected to a resistance causing a current of 0.5A in the circuit. The current drops to 0.4 when an additional resistance of 5Ω is connected in series . The current will drop to 0.2A when the resistance is further increased by 10Ω 15Ω 25Ω 40Ω MCQ – Basic Electrical – Set III 1. Cells are connected in series in order to increase the current capacity life of the cells voltage rating terminal voltage 2. Cells are connected in parallel in order to increase life of the cells efficiency current capacity voltage rating 3. When two cells are connected in parallel , it should ensure that have identical internal resistances equal emfs same ampere hour capacity 4.The capacity of a battery is expressed in amperes amperes-hour watts watt-hour 5. A series resonant circuit implies zero pf and maximum current unity pf and maximum current unity pf and minimum current zero pf and minimum current 6. which one is classified as integrating instrument? D’arsonval galvanometer Ampere-hour meter ohm-meter ammeter 7. Which of the following types of instrument is an integrating instrument? power factor meter energy meter watt meter frequency meter 8. Voltmeter should be of very high resistance so that its range is high its accuracy is high it may draw current minimum possible its sensitivity is high 9. If a voltmeter is connected like a ammeter in series with a load the measurement reading will be too high almost no current will flow in the circuit the meter will burn out an inadmissably high current will flow 10. A multirange instrument (ammeter or voltmeter) has multiple shunt or series resistances inside the meter variable coil turns multi -coil arrangement any of the above MCQ – Basic Electrical – Set IV 1. Measuring range of voltmeter can be extended by using high shunt resistance high series resistance low shunt resistance low series resistance 2. The function of a shunt in an ammeter is to increase the instrument resistance bypass the current reduce the voltage drop across the instrument coil increase the current flowing through the instrument coil 3. A moving instrument has a resistance of 0.6Ω and a full-scale deflection current of 0.1A. To convert it into an ammeter 0-15A range, the resistance of shunt should be 0.6Ω 0.06Ω 0.1Ω 0.004Ω 4. High ac voltage are usually measured with magnetic voltmeter inductive voltmeter potential transformer with voltmeter current transformers and voltmeter 5. Which instrument has lowest resistance? ammeter voltmeter frequency meter meggar 6. All meters used for measuring current, voltage, and resistance are basically voltmeter ammeter multimeter none of the above 7. Which of the following is used to measure the resistance of an electrical installation? multimeter ammeter and voltmeter maxwell’s bridge meggar 8. Meggar is an instrument used for measuring high resistance and insulation resistance medium resistance low resistance leakage current 9. Which of the following statement associated with purely resistive circuits is correct? PF is unity power consumed is zero heat produced is zero PF is zero 10. A leading power factor implies current leads the voltage current lags behind the voltage voltage leads the current none of the above MCQ – Basic Electrical – Set V 1. A series resonant circuit implies zero PF and maximum current unity PF and maximum current unity PF and minimum current zero PF and maximum current 2. DC generator works on the principle f fleming’s lefthand rule Fleming’s righthand rule lenz’s law none of the above 3. EMF induced in each conductor of a dc machine is an alternating emf a direct emf pulsating emf emf of random waveform 4. In large dc generators, the magnetic field is produced by permanent magnet electromagnet either a or b none of the above 5. The emf generated y a dc generator may be increased by increasing speed of rotation excitation armature length either a or b 6. If we increase field current of a dc generator, its emf output increases indefinitely increases till the winding burns increases till the magnetic saturation takes place first increases and then reducing 7. The terminal voltage of a dc shunt generator on loading increases slightly decreases slightly decrease sharply remains constant 8. The transformer action requires a constant magnetic flux increasing magnetic flux alternating magnetic flux alternating electric flux 9. The induced emf in a transformer depends on frequency number of turns maximum value of flux all of the above 10. The flux in transformer core increases with load decreases with load remains constant irrespective of load none of the above MCQ – Basic Electrical – Set VI 1. Open circuit test in a transformer is performed with rated transformer voltage rated transformer current direct current high frequency supply 2. In performing the short circuit test on a transformer high voltage side is usually short circuited low voltage side is usually short circuited any side is usually short circuited none of the above 3. In a transformer both open and short circuit tests are performed on LV side Open circuit test is conducted in HV side and short circuit test on LV side Open circuit test is performed on LV side and short circuit test on HV side both Open and short circuit tests are performed on HV side 4. Power factor of a ac circuit is defined as PF=cosθ PF=R/|z| PF=P(real)/P(app) all of the above 5. Power factor PF is PF α 1/I PF α I PF α I^2 PF α 1/I^2 6. A transmission as well as distribution system of electric power is known as good if High value of voltage regulation and efficiency low value of voltage regulation and high value of efficiency Good power factor and lower voltage regulation none of the above 7. Charcoal, common salt are used in earthing due to following reasons: They increases the conductivity of the soil They increases the contact area of the earth They maintains moisture and increase earth resistance none of the above 8. Voltage source has smaller resistance than load R Higher internal resistance than load R Internal resistance is not present i.e zero in all cases very small internal resistance 9. Material subjected to rapid reversal of magnetism should have high permeability and low hysteresis loss Large B-H loop area large coercivity and high retentivity low permeability and large coercivity 10. Area of hysteresis loop represents copper loss eddy current loss hysteresis loop 11. Silicon content in steel reduces hysteresis loop eddy current loss copper loss