Related Questions

The current coil of a wattmeter is connected to the CT of R-phase. The potential coil is connected across Y and B phases. The wattmeter measures
A Active power in R phase
B Active power of Y phase
C Reactive power of R phase
D Power proportional to 3 phase power if the load is balanced
একটি স্টেপ আপ ট্রান্সফরমারে, গৌণ কুণ্ডলীর পাকসংখ্যা মুখ্য কুন্ডলীর পাকসংখ্যার দ্বিগুণ। যদি মূখ্য কুন্ডলীকে কোন পরিবর্তী বিদ্যুৎ লাইনের সাথে সংযুক্ত করা হয়, তাহলে মুখ্য কুণ্ডলীর তুলনায় গৌণ কুণ্ডলীতে- (In a step up transformer, the number of turns in the secondary coil is twice to that of primary coil. If you apply an alternating current in the primary coil, then in the secondary coil compared to the primary coil-)
A তড়িৎ প্রবাহের মান দ্বিগুণ হবে (current will be doubled)
B তড়িৎ প্রবাহের মান অর্ধেক হবে (current will be halved)
C তড়িৎ বিভবের মান অর্ধেক হবে (voltage will be halved)
D তড়িৎ প্রবাহের মান সমান থাকবে (Current will remain the same)
In a low power factor wattmeter the compensating coil is connected
A in series with current coil
B in parallel with current coil
C in series with pressure coil
D in parallel with pressure coil
The pressure coil of a wattmeter should be connected on the supply side of the current coil when
A Load impedance is high
B Load impedance is low
C Supply voltage is low
D None of the above
In an iron cored coil the iron core is removed so that the coil becomes an air cored coil. The inductance of the coil will
A Increase
B Decrease
C Remain the same
D Initially increase and then decrease
A certain amount of current flows through a ring shaped coil with fixed number of turns. How does the magnetic induction B varies inside the coil if an iron core is threaded into coil without dimensional change of coil?
A Decreases
B Increases
C Remains same
D First increases and then decreases depending on the depth of iron in¬sertion
A coil of wire is placed in a changing magnetic field. If the number of turns in the coil is decreased, the voltage induced across the coil will
A Increase
B Decrease
C Remain constant
D Be excessive
The resistance in the circuit of the moving coil of a dynamometer wattmeter should be
A almost zero
B low
C high
D none of the above
In a compound steam engine, the first stage of expansion is carried out in a high pressure cylinder whereas the last expansion is completed in low pressure cylinder. The diameter of high pressure cylinder is _________ the low pressure cylinder.
A Equal to
B Less than
C More than
D None of these
When a D.C. series motor is connected to A.C. supply, the power factor will be low because of
A high inductance of field and armature circuits
B induced current in rotor due to variations of flux
C fine copper wire winding
D none of the above

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