# For the ac bridge circuit shown in the figure at balance, the value of Rd, Ld, and Qd will be respectively

1.  Ra/Rc Rb ; RaRc/Cb ; ωCbRb

2.  Rb/Ra Rc ; RaRc/Cb ; ωCbRb

3.  Rb/Ra Rc ; Ra Rc Cb ; ωCbRc

4.  Ra/Rb Rc ; Ra Rc Cb ; ωCbRb

4

Ra/Rb Rc ; Ra Rc Cb ; ωCbRb

Explanation :
No Explanation available for this question

# The scale of a 0-500 V voltmeter-is divided into ten large divisions representing 50 V each and each large division a further subdivided into 10 small divisions, each representing 5 V. It is used for measurement of output voltage of a potentiometer which can be varied from 0 to 500 V. It is observed that when the sliding contact moved from its zero position, there is no perceptible movement of pointer of the voltmeter till the sliding contact reaches a position where the output voltage should be 5 V. Therefore, it can be concluded that

1.  threshold of the voltmeter is 5V

2.  resolution of the voltmeter is 5V

3.  sensitivity of the voltmeter is 5V

4.  none of these

4

threshold of the voltmeter is 5V

Explanation :
No Explanation available for this question

# What is the positive, sequence currents in a three phase system, when the original phasors at which are Ia = (12 + j6),Ib = (12 - j12), Ic= (-15 + j10)

1.  14.8 Amp

2.  16.2 Amp

3.  18 Amp

4.   10.2 Amp

4

14.8 Amp

Explanation :
No Explanation available for this question

# What is the positive, sequence currents in a three phase system, when the original phasors at which are Ia = (12 + j6),Ib = (12 - j12), Ic= (-15 + j10)

1.  14.8 Amp

2.  16.2 Amp

3.  18 Amp

4.   10.2 Amp.

4

14.8 Amp

Explanation :
No Explanation available for this question

# A unknown resistance is measured by substitution method. First a standard known resistance of 1000 is connected in series with a circuit having a rheostat and a galvanometer. The battery voltage is 10 V arid the setting of the rheostat is 500 f2 and the galvanometer shows a deflection of 600. After this test, the battery voltage goes down to 9 V and when the unknown resistance is substituted for the known resistance, the galvanometer again shows a deflection of 602 with the same setting of the rheostat The value of unknown resistance is

1.  100Ω

2.  54Ω

3.  90Ω

4.  none of these

4

54Ω

Explanation :
No Explanation available for this question

# The line currents in ampere in phases a, b and c respectively are (400 + j100), (75 - j600) and (-300 +j500)referred-to the same reference vector. The negative sequence components. of currents will be

1.  25 Amp

2.  100 Amp

3.  160 Amp

4.  149.9 Amp

4

149.9 Amp

Explanation :
No Explanation available for this question

# What is the percentage increase of busbar voltage required to compensate for ,the reactance, drop, when the feeder having a reactance of 5% carries a full load current at a p.f. 0.8. lagging

1.  5%

2.  1.2%

3.  1.8%

4.   3%

4

3\%

Explanation :
No Explanation available for this question

# A Wheatstone bridge has ratio arms of 1000W and 100 W resistance, the standard resistance arms consists 4 decade resistance boxes 1000, 100, 10, 1 W steps. The maximum and minimum values, of unknown resistance which can be determined with this set up is

1.  111100Ω,1Ω

2.  111100Ω, 10Ω

3.  111100Ω, 10Ω

4.  none of these

4

111100Ω, 10Ω

Explanation :
No Explanation available for this question

# A small generating station has a busbar divided into three sections each section is connected to a tie bar with reactor each rated at 5 mVA, 0.1 p.u. reactance. A generator of 8mVA, rating and 0.15 p.u. reactance is connected to each section Of the busbar. The Short circuit capacity of e breaker, if a 3-fault takes place on one of the Sections of the busbar will be

1.  78.73 mVA

2.  10.23 mVA

3.  90.8 mVA

4.  85.6 mVA

4

78.73 mVA

Explanation :
No Explanation available for this question

# A Wheatstone bridge cannot be used for precision measurements because errors are introduced into on account of

2.  thermo-electric emfs

3.  contact resistances

4.  all of these

4