Electronics and Communication Engineering - Networks Analysis and Synthesis

1.
Two phasors having rms values V1 and V2 which are added to give a phasor having rms value V3. V3 is maximum if phase angle between V1 and V2 is
90°
180°
270°
360°
Answer: Option
Explanation:

Sum of phasors is maximum if they are in phase and 360° = 0.


2.
A current of 1 A in the coil of an iron cored electromagnet cause a flux density of 0.2.T. If the current is 2 A, B=
0.2 T
0.4 T
0.4 T or less
0.4 T or more
Answer: Option
Explanation:

In air cored coil flux density increases linearly with current because there is no saturation.


3.
If the L.T. of the voltage across a capacitor of value 1/3 F is , then the value of the current through the capacitor at t = 0+ is
0
1
1/3
Answer: Option
Explanation:

t → 0+ s → ∞ and s3 >> s2 >> s >> 1

.


4.
In figure, the current I4 is
10 ∠0
5 ∠90°
5 ∠270°
10 ∠90°
Answer: Option
Explanation:

I4 = I1 + I2 + I3

or I4 = 5∠90° + 5∠0 + 5∠180° = 5∠90°.


5.
For the circuit shown in the figure, the current I is
indeterminate due to indeterminate data
zero
4 Amp
8 Amp
Answer: Option
Explanation:

V must be given.