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The rotation of DC motor can be reversed by
i) Reversing both the field current and armature current

ii) Reversing field current or armature current

iii) Increasing field current

A) Only ii B) Only i and ii

C) Only ii and iii D) All of the above (i, ii and iii)

The working principle of a transformer is based on the
i) Faraday’s law of electromagnetic induction

ii) Thumb rule
iii) Fleming’s right hand rule
iv) Fleming’s left hand rule

A) Only ii and iii B) Onlyi C) Only ii and iv D) Only iii

Accurrent carrying conductor placed in a magnetic field, it experiences a torque, this
principle is related to

Working of a generator

ii) Working of a motor

i)

i)

iii) Working of a transformer
)
)

A) Only i and iii B) Only iii
C) Only ii D) All the above (i, ii and iii)
Percentage of slip in an induction motor is
) (3-70 100
Ns
ii) (NENS) 100
Ns
‏رن‎ N=NS) ‏ووب‎
‎N
‎A) Only i B) Only ii and iii
C) Only iii D) All the above (i, ii and iii)
Which of the following materials have small electrical resistivity ?
i) Bakelite ii) Aluminum
iii) Quartz iv) Copper
A) Only i and iii B) Only iii C) Only ii and iv D) Only i