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Basic Electrical MCQs – General Science MCQs – 3

The cells are connected in series to
(A) Increase the current output (B) Increase the voltage output
(C) Decrease the internal resistance
(D) Decrease the amount of charging voltage required
Answer: Option B

A floating battery is one
(A) Which is getting charge
(B) Which is feeding load
(C) In which battery, voltage is equal to charger voltage
(D) Which gets charged and discharged simultaneously
Answer: Option C

The sparking at the brushes in the D.C generator is attributed to
(A) Quick reversal of current in the coil under commutation
(B) Armature reaction
(C) Reactance voltage
(D) High resistance of the brushes
Answer: Option C

The transformers is not used in the D.C line because
(A) There is no need to step up the D.C voltage
(B) Losses in the D.C circuit are high
(C) Faraday’s low is not valid as the rate of change of flux is zero
(D) D.C transformers are costly
Answer: Option C

The purpose of laminating a transformer core is
(A) Difficulty of fabricating solid core
(B) Laminated core provides high flux density
(C) Avoid eddy current and hysteresis losses
(D) Increase the main flux
Answer: Option C

The mechanical power developed by the D.C motor is maximum when back e.m.f is equal to
(A) Applied voltage
(B) Zero
(C) Half the applied voltage
(D) Twice the applied voltage
Answer: Option C

A series motor at no load develops
(A) Zero speed
(B) Average speed
(C) Rated speed
(D) Infinite speed
Answer: Option D

In the case of D.C shunt motor, the torque with increase in speed will
(A) Increase linearly
(B) Decrease linearly
(C) Increase parabolically
(D) Remain unchanged
Answer: Option D

If the supply terminals of D.C shunt motor are interchanged, then
(A) Motor will stop
(B) Motor will run at its normal speed in the same direction as it was running
(C) The direction of rotation will reverse
(D) Motor speed will increase
Answer: Option C

In the case of D.C shunt generator, as the load current increases, the terminal voltage
(A) Decreases gradually slightly from a maximum value
(B) Increases linearly from zero
(C) Decreases linearly from maximum to zero
(D) Remain constant
Answer: Option A