Power Generator

31. An example of rechargeable dc source is an/a

1. lithium battery
2. photovoltaic cell
3. optoisolator
4. lead acid battery

View answer

32. An ideal transformer is one which

1. has no losses and leakage reactance
2. does not work
3. has the same number of primary and secondary turns
4. has the same primary and secondary voltage

View answer

33. Armature reaction in a dc motor is increased

1. When the armature current increases
2. when the armature current decreases
3. when the field current increases
4. by interpole

View answer

34. As the load increases a, ___________ motor will speed uo

1. series
2. commutatively compounded
3. shunt
4. differentially compounded

View answer

35. Back emf in a dc motor is maximum at

1. no load
2. half full load
3. full load
4. three fourth full load

View answer

36. By laminating the core of a transformer, ___________ decreases

1. leakage reactance
2. eddy current loss
3. hysteresis loss
4. copper loss

View answer

37. Carbon brushes are used in a dc machine because

1. carbon lubricates and polishes the commutator
2. contact resistance is decreased
3. carbon is cheap
4. carbon is abundant

View answer

38. Combination of ac motor, dc generator, and exciter to provide adjustable voltage dc power to a dc motor.

1. Ward-Leonard system
2. Half wave SCR adjustable voltage supply
3. Compound motor
4. Universal motor

View answer

39. Connecting batteries of equal voltage in parallel

1. multiplies the voltage available
2. increases the internal resistance
3. reduces the power available
4. multiplies the current available

View answer

40. considered as the main types of battery

1. Lithium cell and alkaline
2. Carbon-zinc dry cell and lead sulphuric wet cell
3. Leclanche cell and carbon zinc
4. Voltaic cell and lithium cell

View answer