Deck 8: Electronics and Power Supply

Question 1

What is the output as a function of the input voltage (for positive values) for the given figure. Assume it's an ideal op-amp with zero forward drop (Di=0)

A)0
B)-vi
C)vi
D)2vi

Answer 1

vi

Question 2

In a half wave rectifier, the sine wave input is 50sin50t. If the load resistance is of 1K, then average DC power output will be?

A)3.99v
B)2.5v
C)5.97v
D)6.77v

Answer 2

2.5v

Question 3

Efficiency of a half wave rectifier is

A)50%
B)60%
C)40.6%
D)46%

Answer 3

40.6%

Question 4

If peak voltage for a half wave rectifier circuit is 5V and diode cut in voltage is 0.7, then peak inverse voltage on diode will be?

A)5v
B)4.9v
C)4.3v
D)6.7v

Question 5

Transformer utilisation factor of a half wave rectifier is                    

A)0.234
B)0.279
C)0.287
D)0.453

Question 6

If the input frequency of a half wave rectifier is 100Hz, then the ripple frequency will be                   

A)150hz
B)200hz
C)100hz
D)300hz

Question 7

Efficiency of a centre tapped full wave rectifier is                    

A)50%
B)46%
C)70%
D)81.2%

Question 8

A full wave rectifier delivers 50W to a load of 200?. If the ripple factor is 2%, calculate the AC ripple across the load.

A)2v
B)5v
C)4v
D)1v

Question 9

In a centre tapped full wave rectifier, RL=1K? and for diode Rf=10?. The primary voltage is 800sin?t with transformer turns ratio=2. The ripple factor will be                    

A)54%
B)48%
C)26%
D)81%

Question 10

Due to centre tap Vm=400/2=200) IRMS=198/?2=140mA, IAVG=2*198/ ?=126mA. ?=[(140/126)2-1]1/2=0.48. So, ?=48%.

A)0.623
B)0.678
C)0.693
D)0.625

Question 11

If the peak voltage on a centre tapped full wave rectifier circuit is 5V and diode cut in voltage is 0.7. The peak inverse voltage on diode is

A)4.3v
B)9.3v
C)5.7v
D)10.7v

Question 12

What is done in switching regulators to minimize its power dissipation during switching?

A)uses external transistor
B)uses 1mh choke
C)uses external transistor and 1mh choke
D)none of the mentioned

Question 13

Choose the correct statement

A)mosfet is a unipolar, voltage controlled, two terminal device
B)mosfet is a bipolar, current controlled, three terminal device
C)mosfet is a unipolar, voltage controlled, three terminal device
D)mosfet is a bipolar, current controlled, two terminal device

Question 14

The arrow on the symbol of MOSFET indicates

A)that it is a n-channel mosfet
B)the direction of electrons
C)the direction of conventional current flow
D)that it is a p-channel mosfet

Question 15

The controlling parameter in MOSFET is

A)vds
B)ig
C)vgs
D)is

Question 16

In the internal structure of a MOSFET, a parasitic BJT exists between the

A)source & gate terminals
B)source & drain terminals
C)drain & gate terminals
D)there is no parasitic bjt in mosfet

Question 17

In the transfer characteristics of a MOSFET, the threshold voltage is the measure of the

A)minimum voltage to induce a n-channel/p- channel for conduction
B)minimum voltage till which temperature is constant
C)minimum voltage to turn off the device
D)none of the above mentioned is true

Question 18

The output characteristics of a MOSFET, is a plot of

A)id as a function of vgs with vds as a parameter
B)id as a function of vds with vgs as a parameter
C)ig as a function of vgs with vds as a parameter
D)ig as a function of vds with vgs as a parameter

Question 19

SMPS is used for

A)obtaining controlled ac power supply
B)obtaining controlled dc power supply
C)storage of dc power
D)switch from one source to another

Question 20

Choose the incorrect statement.

A)smps is less sensitive to input voltage variations
B)smps is smaller as compared to rectifiers
C)smps has low input ripple
D)smps is a source of radio interference

Question 21

-----------------is used for critical loads where temporary power failure can cause a great deal of inconvenience.

A)smps
B)ups
C)mps
D)rccb

Question 22

------------------is used in the rotating type UPS system to supply the mains.

A)dc motor
B)self excited dc generator
C)alternator
D)battery bank

Question 23

Static UPS requires                      

A)only rectifier
B)only inverter
C)both inverter and rectifier
D)none of the mentioned