Objective physics for all graduation level exams

In this particular article Objective physics for all graduation level exams and msc entrance, we will cover the topic field-effect-transistor.

Part A

Q.1 A JFET is… Device

(1) Uni-polar

(2) bipolar

(3) uni-junction

(4) none of the above

Answer: Uni-polar

(Only one type of carrier, electron or hole)

Q.2 The gate of a JFET is…biased

(1) reverse

(2) forward

(3) reverse as well as forward

(4) none of the above

Answer: Reverse

Q.3 The input impedance of a JEFT is…that of an ordinary Transistor

(1) equal to

(2) less than

(3) more than

(4) none of the above

Answer: More than

Q.4 In a p-channel JEFT, the charge carriers are…

(1) electrons

(2) holes

(3) both electrons and holes

(4) none of the above

Answer: holes

Q.5 When drain voltage equals the pinch-off-voltage, then drain current…with the increase in drain voltage

(1) decreases

(2) increases

(3) remains constant

(4) none of the above

Answer: Remain constant

(Pinch off voltage is the drain to source voltage after which the drain to source current becomes almost constant)

Part B

Q.6 If the reverse bias on the gate of a JFET is increased, then width of the conducting channel…

(1) is decreased

(2) is increased

(3) remains the same

(4) none of the above

Answer: is decreased

Q.7 A MOSFET has… Terminals

(1) two

(2) five

(3) four

(4) three

Answer: Three

(Source, Drain, Gate)

Q.8 A MOSFET can be operated with…

(1) negative gate voltage only

(2) positive gate voltage only

(3) positive as well as negatively gate voltage

(4) none of the above

Answer: positive as well as negative gate voltage

Q.9 The input control parameter of a JEFT is…

(1) gate voltage

(2) source voltage

(3) drain voltage

(4) gate voltage

Answer: gate voltage

Q.10 A JEFT has high input impedance because

(1) it is made of semiconductor material

(2) input is reverse biased

(3) of  impurity atoms

(4) none of the above

Answer: input is reverse biased

Part C

Q.11 In a JFET, when drain voltage is equal to pinch off voltage, the depletion layers…

(1) almost touch each other

(2) have large gap

(3) have moderate gap

(4) none of the above

Answer: almost touch each other

Q.12 In a JFET, Idss is known as…

(1) drain to source current

(2) drain to source current with gate shorted

(3) drain to source current with gate open

(4) none of the above

Answer: drain to source current with gate shorted

Q.13 The two important advantages of a JEFT are…

(1) high input impedance and square-law property

(2) inexpensive and high output impedance

(3) low input impedance and high output impedance

(4) none of the above

Answer: high input impedance and square-law property

Q.14 A MOSFET is sometimes called…JFET

(1) many gate

(2) open gate

(3) insulated gate

(4) shorted gate

Answer: insulated gate

Q.15 Which of the following devices has the highest input impedance?

(1) JFET

(2) MOSFET

(3) crystal diode

(4) ordinary Transistor

Answer: MOSFET

Part D

Q.16 A MOSFET uses the electric field of a…to control the channel current

(1) capacitor

(2) battery

(3) generator

(4) none of the above

Answer: Capacitor

Q.17 The gate voltage in a JFET at which dra current becomes zero is called…voltage

(1) saturation

(2) pinch-off

(3) active

(4) cut-off

Answer: pinch-off

Q.18 In a FET, there are…pn junctions at the sides

(1) three

(2) four

(3) five

(4) two

Answer: Two

Q.19 If the cross-section area of the channel in n-channel JEFT increases, the drain current…

(1) is increased

(2) is decreased

(3) remains the same

(4) none of the above

Answer: is increased

Q.20 The channel of JEFT is between the…

(1) gate and drain

(2) drain and source

(3) gate and source

(4) input and output

Answer: drain and source

Part E

Q.21 A certain JEFT data sheet gives Vgs(off) = -4V. The pinch-off  voltage Vp is…

(1)+4V

(2) -4V

(3) dependent on Vgs

(4) data insufficient

Answer: +4V

Q.23 The constant-current region of a JEFT lies between

(1) cut off and saturation

(2) cut off and pinch-off

(3) o and Idss

(4) pinch-off and breakdown

Answer: pinch-off and breakdown

Q.24 A MOSFET differs from a JFET mainly because

(1) of power rating

(2) The MOSFET has two gates

(3) the JFET has a pn junction

(4) none of the above

Answer: the JEFT has a pn junction

Q.25 A n-channel D-MOSFET with a positive Vgs is operating in…

(1) the depletion-mode

(2) the enhancement-mode

(3) cut off

(4) saturation

Answer: the enhancement-mode

 

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