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Electronics and Communication Engineering - Electronic Devices and Circuits

Exercise : Electronic Devices and Circuits - Section 3
11.
The breakdown voltage in a zener diode
is almost constant
is very small
may destroy the diode
decreases with increase in current
Answer: Option
Explanation:

Therefore, it is used in voltage regulator circuits.

12.
A varactor diode is used for
tuning
rectification
amplification
rectification and amplification
Answer: Option
Explanation:

Its voltage dependent capacitance is used for tuning.

13.
One eV = 1.602 x 10-19 joules.
True
False
Answer: Option
Explanation:

One electron has a charge 1.602 x 10-19 C, when it falls through 1 V, energy is 1 eV = 1.602 x 10-19 J.

14.

Assertion (A): When VDS is more than rated value the drain current in a JFET is very high.

Reason (R): When VDS is more than rated value, avalanche breakdown occurs.

Both A and R are true and R is correct explanation of A
Both A and R are true but R is not a correct explanation of A
A is true but R is false
A is false but R is true
Answer: Option
Explanation:

Avalanche breakdown causes high current.

15.
If ib is plate current, eb is plate voltage and ec is grid voltage the v-i curve of a vacuum triode is
ib = 0.003 (eb + kec)n. Typical values of k and n are
0.5 and 1
- 2 and 1
30 and 1
30 and 1.5
Answer: Option
Explanation:

k has to be much higher than 1 so that grid is effective in controlling plate current n is not 1 because it is a nonlinear device.

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