The depth of penetration of wave in a lossy dielectric increases with increasing

A)     Conductivity

B)      Permeability

C)      Wavelength

D)     Permittivity

The intrinsic impedance of copper at high frequencies is (GATE 1998)

A)     Purely resistive

B)      Purely inductive

C)      Complex with a capacitive component

D)     Complex with an inductive component

Explanation: The intrinsic impedance is given by √(jwµ√ϭ + jw€). Since copper is a good conductor, ϭ << jw€, thus the intrinsic impedance will have +j component only. This refers to complex with an inductive component.

When electromagnetic waves are propagated in a wave guide

A)     They travel along the border walls of the guide

B)      They are reflected from the walls but do not travel along them

C)      They travel through the dielectric without touching the walls

D)     They travel along all four walls of the wave guide

As a result of reflections from a plane conducting wall, electromagnetic waves acquire an apparent velocity greater than the velocity of light in space. This is called the

A)     Velocity of propagation

B)      Normal velocity

C)      Group velocity

D)     Phase velocity

Transmission of power to a load over transmission line achieves optimum value when standing-wave ration (SWR) becomes

A)     2:1

B)      1:2

C)      1:1

D)     1:4

White noise is that signal whose frequency spectrum

A)     Extends over infinite range

B)      Has flat spectral density

C)      Has spectral density varying as 1/f

D)     Has limited number of frequency components

The maximum value of mutual inductance of two inductively coupled coils with self inductances L1=49mH and L2=81mH is

A)     130 mH

B)      63 mH

C)      32 mH

D)     3969 mH