Electronic Devices and Circuits - Section 1 (3)

Directions to Solve

Electronic Devices and Circuits - Section 1

17.

In a bipolar transistor which current is largest

A.	collector current
B.	base current
C.	emitter current
D.	base current or emitter current

Answer: Option C

Explanation:

Emitter current is larger, collector current is slightly less than emitter current and base current is very small.

18.

In a zener diode

A.	the forward current is very high
B.	sharp breakdown occurs at a certain reverse voltage
C.	the ratio v-i can be negative
D.	there are two p-n junctions

Answer: Option B

Explanation:

When reverse voltage equals breakdown value it starts conducting and voltage does not increase further.

19.

A particular green LED emits light of wavelength 5490, Å, the energy bandgap of the semiconductor material used there is .. h = 6.6 x 10^-34 J sec.

A.	2.26 eV
B.	1.98 eV
C.	1.17 eV
D.	0.74 eV

Answer: Option A

Explanation:

From Plank equation 76-400-1 joule

to convert it into electron volt it will be divided by 1.6 x 10^-19.

20.

A zener diode is used in

A.	voltage regulator circuit
B.	amplifier circuits
C.	both voltage regulator and amplifier circuit
D.	none of the above

Answer: Option A

Explanation:

Zener diode is used only in voltage regulator circuits.

21.

An increase in temperature increases the width of depletion layer.

A.	True
B.	False

Answer: Option B

Explanation:

With increase in temperature width of depletion layer decreases.

22.

In an n-p-n transistor biased for operation in forward active region

A.	emitter is positive with respect to base
B.	collector is positive with respect to base
C.	base is positive with respect to emitter and collector is positive with respect to base
D.	none of the above

Answer: Option C

Explanation:

In forward active mode emitter base junction is forward biased and base collector junction is reverse biased.

23.

Assertion (A): The conductivity of p type semiconductor is higher than that of intrinsic semiconductor.

Reason (R): The addition of donor impurity creates additional energy levels below conduction band.

A.	Both A and R are true and R is correct explanation of A
B.	Both A and R are true but R is not a correct explanation of A
C.	A is true but R is false
D.	A is false but R is true

Answer: Option B

Explanation:

A refers to type semiconductor while R refers to n type semiconductor. Both A and R are correct but independent.

24.

If a_ac for transistor is 0.98 then β_ac is equal to

A.	51
B.	49
C.	47
D.	45

Answer: Option B

Explanation:

74-160-1

Electronic Devices and Circuits - Section 1 (3)

Electronic Devices and Circuits - Section 1

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