Related Questions

If A varies directly proportional to C and B also varies directly proportional to C, which one of the following is not correct ?
A $$\left( {A + B} \right)\alpha \,C$$
B $$\left( {A - B} \right)\alpha \,\frac{1}{C}$$
C $$\sqrt {AB} \,\alpha \,C$$
D $$\frac{A}{B} = {\text{constant}}$$
A synchronous motor is running with normal excitation. When the load is increased, the armature current drawn by it increases because
A Speed of the motor is reduced
B Power factor is decreased
C Eb (back e.m.f.) becomes less than V (applied voltage)
D Er (net resultant voltage) in armature is increased
As the load is applied to a synchronous motor, the motor takes more armature current because
A The increased load has to take more current
B The rotor by shifting its phase backward causes motor to take more current
C The back e.m.f. decreases causing an increase in motor current
D The rotor strengthens the rotating field causing more motor current
The armature torque of the D.C. shunt motor is proportional to
A field flux only
B armature current only
C both (A) and (B)
D none of the above
As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit
A A resistance is connected in series with armature
B A resistance is connected parallel to the armature
C Armature is temporarily open circuited
D A high value resistor is connected across the field winding
In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be
A Almost negligible
B Rated full-load current
C Less than full-load current
D More than full-load current
When load on an over-excited or under excited synchronous motor is increased, rate of change of its armature current as compared with that of power factor is
A more
B less
C equal
D twice
The armature current of the synchronous motor has higher values for
A high excitation only
B low excitation only
C both (A) and (B)
D none of the above
In a synchronous motor, the armature current has large values for
A high excitation only
B low excitation only
C both high and low excitation
D none of the above
The armature current of the synchronous motor
A has large values for low excitation i niy
B has large values for high excitation only
C has large values for low and high excitation
D any of the above

Next steps