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Electronics and Communication Engineering - Electronic Devices and Circuits

Exercise : Electronic Devices and Circuits - Section 12
26.
If operator 'a' = 1 ∠120° then (1 + a2) =
3
3 ∠30°
3 ∠ - 30°
3 ∠60°
Answer: Option
Explanation:

1 - a2 = 1 + 0.5 + j 0.866 = 3∠30°.

27.
Two 2 port circuits are connected cascaded. To determine the response, it is more convenient to use
O.C. impedance parameters
S.C. admittance parameters
ABCD parameters
h parameters
Answer: Option
Explanation:

ABCD matrix of two-four terminal network is the product of individual ABCD matrices.

28.
In the circuit of figure. The current supplied by battery at t = ∞ is
0 A
5 A
less than 5 A
very large
Answer: Option
Explanation:

At t = ∞, inductance is short-circuited and capacitor is open circuited.

29.
The natural frequency Sn of the given circuit is
- 1
+ 1
1/2
- 2
Answer: Option
Explanation:

[When current open and seen from inductance side]

Sn + 1 = 0 Sn = -1.

30.
For addition and subtraction operations, phasors
must be represented in polar form
must be represented in rectangular form
may be represented in any form
none of the above
Answer: Option
Explanation:

Addition and subtraction is not possible in polar form.

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