# If stator field is rotating in clockwise direction rotor rotates in

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If stator field is rotating in clockwise direction rotor rotates in (A) any direction (B) cannot predict (C) anticlockwise (D) clockwise

If stator field is rotating in clockwise direction rotor rotates in clockwise

## Related questions

An electric motor in which both stator field and rotor rotates with same speed is called?

A rotating electrical machine its self-inductances of both the stator and the rotor windings, independent of the rotor position will be definitely not develop  (A) starting torque (B) synchronizing torque (C) hysteresis torque (D) reluctance torque

in a three-phase induction motor, the rotor field runs at the following speed with respect to the stator structure:

A 3-phase, 4-pole, 50Hz induction motor runs at a speed of 1440 rpm. The rotating field produced by the rotor rotates at a speed of ________ rpm with respect to stator field. (A) 1500 (B) 0 (C) 1440 (D) 60

If the conductive loop on the rotor of a simple two -pole, single-phase generator rotates at the rate of 400 rps. The frequency of the induced output voltage will be: A. 40 Hz B. 100 Hz C. 400 Hz D. indeterminable

If the stator winding of a three-phase induction motor is delta connected, the rotor winding   (a) should be delta connected (b) should be star connected (c) should not be delta connected (d) may be delta or star connected

The direction of rotation of a 3-phase induction motor is clockwise when it is supplied with 3-phase sinusoidal voltage having phase sequence A-B-C. For counter clockwise rotation of the motor, the phase sequence of the power supply should be  (A) B-C-A (B) C-A-B (C) A-C-B (D) B-C-A or C-A-B

In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation, the machine is operating as  (1) synchronous motor (2) synchronous generator (3) asynchronous motor (4) asynchronous generator

The phase sequence of a 3 phase alternator is RBY. If the direction of rotation of field is reversed, then which of the following can be the phase sequence ? (A) RBY (B) BYR (C) BRY (D) YRB

In a single-phase induction motor when the rotor is stationary and voltage is applied to the stator, then (A) the flux is constant (B) the flux first decreases and then increases in the same direction (C) the flux increases and decreases in the opposite direction with the same magnitude (D) current flows through the rotor

A permanent magnet stepper motor with 8 poles in stator and 6 poles in rotor will have a step angle of (a) 7.5° (b) 15° (c) 30° (d) 60°

A shunt motor rotating at 1500 r/min is fed by a 120 V source. The line current is 51 A and the shunt field resistance is 120 ohm. If the armature resistance is 0.1 ohm, calculate the current in the armature.  (A) 1 A (B) 51 A (C) 50 A (D) 12 A

In an ac tachometer, the two stator field coils are mounted

A three phase slip ring induction motor is fed from the rotor side with stator winding short circuited stator is: (1) Slip frequency (2) Supply frequency (3) Frequency corresponding to rotor speed (4) Zero

A commutator with a diameter of 50 cm rotates at 1000 r.p.m. If brush width is 1.5 cm, the time of commutation will be (a) 0.168 m sec (b) 0.374 m sec (c) 0.481 m sec (d) 0.573 m sec

The stator mmf and rotor mmf of a 3-phase induction motor (A) are equal (B) rotate with slip speed (C) are opposite but rotate with synchronous speed (D) rotate with the same rotor speed

A three-phase, three-stack, variable reluctance step motor has 20 poles on each rotor and stator stack. The step angle of this step motor is  (A) 3o (B) 6o (C) 9o (D) 18o

A 3-phase induction motor under locked rotor condition and with stator supply, induces (A) small voltage at slip frequency (B) large voltage at rotor frequency (C) zero voltage at zero frequency (D) large voltage at slip frequency

An 1.8° step, 4 -phase stepper motor has 40 teeth on 8 poles of the stator. The number of rotor teeth for their rotor will be: (A) 40 (B) 50 (C) 100 (D) 80

What is the direction of the induced electric field?

What is the direction of the electric field?

If the rotating mass of a rim type flywheel is distributed on another rim type flywheel whose mean radius is half the mean radius of the former, then the energy stored in the latter at the same speed will be : (A) Four times the first one (B) Same at the first one (C) One fourth of the first one (D) One and half times the first one

A cylindrical rotor synchronous motor is switched on to the supply with its field windings shorted on themselves, the motor will .  A) Not start B) Start but will not run at synchronous speed C) Start as an induction motor and then run as a synchronous motor D) Start and run as a synchronous motor

In a parallel plate capacitor of capacitance Co, the electric field is E. If a dielectric slab with dielectric constant = 7 is introduced to fill capacitor completely, the electric field will become (a) 7E (b) E/7 (c) E/3.5 (d) E. Co

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 polarity of induced voltage while a field is collapsing is : - a) independent of the force creating the field b) opposite to the force creating c) the field identical to the force creating d) the field present only if the force is stationary

The stator of a 3 phase, 10 pole induction motor possesses 120 slots. If a lap winding is used, calculate the coil pitch, if the coil width extends from slot 1 to slot 11.  (A) 72.12% (B) 83.30% (C) 12% (D) 42%

Which of the following quantity maintains the same direction whether a D.C. machine runs as a generator or as a motor a. Induced e.m.f. b. Armature Current c. Field Current d. Supply Current

Which of the following laws relates the magnetic field to the magnitude, direction, length, and proximity of the electric current? A) Lenz’s law B) Faraday’s law C) Biot–Savart law D) None of these

The rotor of a synchro transmitter: -  a) uses a salient pole type of construction b) uses a cylindrical pole type of construction c) may use either salient pole or cylindrical type of construction d) none of the above

What type of insulator will be used if the direction of the transmission line is to be changed?

If a 3-phase, 400V, 50Hz, 4 pole induction motor is running at a slip of 5% then the relative speed of rotor field with respect to stator filed is:

If the supply frequency of a 3-phase induction motor is ‘f’, then frequency of rotor emf at motor slip ‘s’ will be   (a) sf (b) (1 – s)f (c) f/s (d) None of these

In an induction type energy meter, the steady speed attained by the rotating disc is  1. Proportional to the deflecting torque. 2. Proportional to the resistance of the path of eddy currents. 3. Inversely proportional to the effective readings of disc from its axis. 4. Inversely proportional to the square of brake magnet flux.  Which of the above are correct ?

A 200 V dc motor takes a field current of 2 A to generate a back emf of 180 V. If the field winding resistance is 80 Ω, the resistance of the shunt field regulator is (A) 10 Ω (B) 20 Ω (C) 100 Ω (D) 180 Ω

A cumulatively compounded d.c. generator is supplying 20 A at 200 V. If the series field winding is short circuited, the terminal voltage will (a) remain unaltered (b) rise to 220 V (c) shoot up to a very high value (d) become less than 200 V

A synchronous motor operates at 0.8 pf lagging. If the field current of the motor is continuously increased  1. The power factor decreases upto a certain value of field current and thereafter it increases.  2. The armature current increases upto a certain value of field current and thereafter it decreases.  3. The power factor increases upto a certain value ... field current and thereafter it, increases.  From these, the correct answer is (a) 1, 2 (b) 3, 4 (c) 1, 3 (d) 2, 4

A separately excited dc generator is running at rated speed and at no load. If its field winding is suddenly connected to a dc source then rise in armature generated voltage is governed by (1) Armature time constant (2) Field time constant (3) Both (a) and (b) (4) Mechanical time constant

A cumulative dc compound motor runs at 1500 rpm. on full load. If its series field is short-circuited, its speed  (1) becomes zero (2) remains unchanged (3) increases (4) decreases