Electrical Engineering Practice Bits -5

Electrical Engineering Practice Bits -5

1.     The brush voltage drop in dc motor is usually in the order of

a.     2v

b.    10V

c.     20V

d.    50V

2.     The most effective damping is

a.     Fluid friction

b.    Electromagnetic

c.     Air friction

d.    Eddy current

3.     A doped semi conductor is also known as

a.     A semiconductor

b.    Diffused semi conductor

c.     Intrinsic semi conductor

d.    Extrinsic semi conductor

     

4.     Which of the following has the highest mobility?

a.     Neutron

b.    Electron

c.     Positive ion

d.    Negative ion

6.     The gain of voltage amplifier is 60dB. It is numerically equal to

a.     60

b.    100

c.     1000

d.    10000

7.     In an oscillator

a.     There is no feedback

b.    There is a negative feedback

c.     There is a positive feedback

d.    There can be either positive or negative feedback

8.     The PIV of each diode in a fuel wave bridge rectifier is

a. Vm

b.    2Vm

c.     Vm

d.    None

9.     In a thyristor holding current is

a.     More than latching current I_l

b.    Less than I_l

c.     Equal to I_l

d.    Very small

10.  If “N_S” is the synchronous speed, then speed of the motor N_r

a.     N_S

b.    SN_S

c.     (1-S)N_S

d.    (N_S-1)S

11.  The frequency of the rotating magnetic field produced in the rotor is equal to

a.     Slip x supply frequency

b.    Supply frequency

c.     Supply frequency

d.    None

12.  For ceiling fans, generally the single phase motor used is

a.     Split phase type

b.    Capacitor start type

c.     Capacitor start and run type

d.    Permanent capacitor

13.  In a 3-phase  supply. The phase angle between any two phase is

a.     60⁰

b.    90⁰

c.     120⁰

d.    180⁰

14.  The power developed by a synchronous machine maximum when load angle

a.     Zero

b.    45⁰

c.     90⁰

d.    120⁰

15.  The speed regulation of a synchronous machine is always

a.     1%

b.    0.5%

c.     -1%

d.    Zero

16.  The most common generation voltage in india

a.     66KV

b.    33KV

c.     11KV

d.    3.3KV

17.  Salient poles are generally use on

a.     High speed

b.    Low speed

c.     Both a and b

d.    None

18.  The material used for control rod is

a.     Heavy water

b.    Carbon

c.     Boron

d.    Uranium

19.  The efficiency of electrostatic precipitator is as high as

a.     99.8%

b.    90%

c.     85%

d.    80%

20.  Water hammer is developed in

a.     Surge tank

b.    Water turbine

c.     Penstock

d.    Draft tube