20EE2E55-EMD-SQ1

The unit of magnetic flux density is ___________.

• AT/Wb

• Wb/AT

• Wb/m²

• AT/m

In DC generators, lap connected winding is used for _______ voltage and ______ current applications.

• low, low

• low, high

• high, high

• high, low

The _________ loss is directly proportional to square of frequency.

• eddy current

• hysteresis

• variable

• copper

Commutator of DC machines is made up of __________.

• aluminum

• silver

• copper

• carbon

The direction of DC motor is given by _________ rule.

• Lenz’s law

• Flemming’s right hand rule

• Ampere’s law

• Flemming’s left hand rule

Magnetically induced EMF is caused by______________

• Variation in magnetic flux
  
  

• Static magnetic field

• Magnetic field due to moving charges

• Magnetic field due to permanent magnets

The force experienced by a current-carrying conductor in a magnetic field is _________.

• Lorentz force

• electrostatic force

• gravitational force

• nuclear force

The property of the material which opposes the creation of magnetic flux is known as _______.

• resistance

• conductance

• permeance

• reluctance

A 230V DC motor takes armature current of 2.5A and runs at 1000rpm. If the resistance of armature is 0.25Ω, then the back emf developed is _________.

• 229 V

• 231 V

• 243 V

• 257 V

A 4-pole machine has an armature with 80 slots and 8 conductors/slot and runs at 1500rpm, the flux per pole is 0.05 Wb. If the winding is wave connected, the induced emf is _______.

• 1500V

• 1800V

• 1700 V

• 1600V