Electronics and Communication Engineering - Networks Analysis and Synthesis

46.
A parallel plate capacitor with air as dielectric has a capacitance C. If the dielectric has a dielectric constant ∈r and the remaining dimensions are the same, the capacitance will be
C/∈r
rC
2rC
3rC
Answer: Option
Explanation:

Capacitance ∝ ∈r.


47.

Assertion (A): When excited by a unit step voltage, an inductor behaves as open circuit at t = 0.

Reason (R): Inductance has the property of inertia.

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

Because of inertia the current cannot change instantaneously. Therefore it behaves as O.C. at t = 0.


48.
A bulb rated at 60 W, 120 V is used for 30 minutes. The charge associated with this operation is
3600 C
900 C
7200 C
600 C
Answer: Option
Explanation:


49.
Two coil have their axis perpendicular to each other. The coefficient of coupling k is
1
0.5
more than 0 but less than 1
0
Answer: Option
Explanation:

When axis are perpendicular then there is no mutual coupling.


50.
In a series RLC circuit, p-f is leading if XC < XL.
True
False
Answer: Option
Explanation:

If XC < XL power factor is lagging.