When /?2 is the rotor resistance, .X2 the rotor reactance at supply frequency and s the slip, then the condition for maximum torque under running conditions will be_____________?

A. Sr2x2 = 1
B. Sr2 = x2
C. R2 = sx2
D. R2 = s2x2

In case of a double cage induction motor, the inner cage has__________?

A. High inductance arid low resistance
B. Low inductance and high resistance
C. Low inductance and low resistance
D. High inductance and high resistance

In an induction motor if air-gap is increased__________?

A. The power factor will be low
B. Windage losses will be more
C. Bearing friction will reduce
D. Copper loss will reduce in an induction motor

The torque developed by a 3-phase induction motor least depends on__________?

A. Rotor current
B. Rotor power factor
C. Rotor e.m.f.
D. Shaft diameter

Which motor is preferred for use in mines where explosive gases exist ?

A. Air motor
B. Induction motor
C. D.c. shunt motor
D. Synchronous motor

The circle diagram for an induction motor cannot be used to determine____________?

A. Efficiency
B. Power factor
C. Frequency
D. Output

Blocked rotor test on induction motors is used to find out?

A. Leakage reactance
B. Power factor on short circuit
C. Short-circuit current under rated voltage
D. All of the above

The complete circle diagram of induetion motor can be drawn with the help of data found from__________?

A. Noload test
B. Blocked rotor test
C. Stator resistance test
D. All of the above

In the squirrel-cage induction motor the rotor slots are usually given slight skew__________?

A. To reduce the magnetic hum and locking tendency of the rotor
B. To increase the tensile strength of the rotor bars
C. To ensure easy fabrication
D. None of the above

The torque of a rotor in an induction motor under running condition is maximum__________?

A. At the unit value of slip
B. At the zero value of slip
C. At the value of the slip which makes rotor reactance per phase equal to the resistance per phase
D. At the value of the slip which makes the rotor reactance half of the rotor