134. The generated emf and the current are in the opposite direction in case of
A. dc motors
B. dc generators
C. both dc motors as well as dc generators
D. neither dc motors nor dc generators.

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135. In a simple magnetic relay, armature is in open position. As the armature moves to wards the yoke under the influence of magnetic force f e air-gap flux density Bg and fe very as under :
A. B increase and f decreases
B. Both decrease
C. Both increase
D. B decreases and f increases.

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136. Starter for a dc motor also provides protection to the motor against damage
A. due to short circuits in the equipment
B. from the long-term over loads
C. from excessive starting currents
D. all of the above

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137. List I represent the different types of electric motors, whilst list II gives some of their characteristics : Match the two lists by choosing the correct answer from the following :
A. DC series motor
B. DC shunt motor
C. 3-phase induction motor
D. Synchronous motor

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138. Match list I with the appropriate answer in the list II and select the correct answer from the codes riven below the lists :Motor Typical Application (A) Permanent magnet dc motor (B) Stepper motor (C) Single-phase induction motor (D) Universal motorCodes :
A. A ? P, B ? S. C ? R, D ? Q
B. A ? P, B ? Q, C? R, D ? S
C. A ? P, B ? S, C ? Q, D ? R
D. A ? Q, B ? S, C ? P, D ? R

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139. A4 pole d.c. generator is running at 1500 r.p.m. The frequency of current in the armature winding is
A. 25 Hz
B. 50 Hz
C. zero Hz
D. 100 Hz

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140.  Speed control by the variation of field flux result in
A. constant power drive
B. variable power drive
C. constant power drive
D. variable torque drive

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