Which of the following statement is NOT correct ? - Vidyadip

MCQ

Which of the following statement is $NOT$ correct ?

A
Ground wave signals are more stable than the sky wave signals.
B
The critical frequency of an ionospheric layer is the highest frequency that will be reflected back by the layer when it is vertically incident
✓
Electromagnetic waves of frequencies higher than about $30\, MHz$ cannot penetrate the ionosphere
D
Sky wave signals in the broadcast frequency range are stronger at night than in the day time

✓

Answer

Correct option: C.

Electromagnetic waves of frequencies higher than about $30\, MHz$ cannot penetrate the ionosphere

c
Above critical frequency $(f_c)$ , an electromagnetic wave penetrates the ionosphere and is not reflected by it

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "M.C.Q (1 Marks)" from Communication→Communication — all question types→Physics STD 12 Science question papers→CBSE Board STD 12 Science question papers→CBSE Board question paper generator→

Similar questions

The area of hysteresis loop of a material is equivalent to $250$ $joule$. When $10 \,kg$ material is magnetised by an alternating field of $50\, Hz$ then energy lost in one hour will be if the density of material is $7.5\,gm/c{m^3}$

Two short magnets of equal dipole moments M are fastened perpendicularly at their centre $($figure$)$. The magnitude of the magnetic field at a distance d from the centre on the bisector of the right angle is:

The charge on a capacitor of capacitance $10\,\mu F$ connected as shown in the figure is.......$\mu C$

Gauss is unit of which quantity

A parallel plate capacitor is connected to a battery. The plates are pulled apart with a uniform speed. If $x$ is the separation between the plates, the time rate of change of electrostatic energy of capacitor is proportional to

The resistance of a wire of uniform diameter $d$ and length $L$ is $R$. The resistance of another wire of the same material but diameter $2d$ and length $4L$ will be

In good conductors of electricity, the type of bonding that exists is

The condition for observing Fraunhofer diffraction from a single slit is that the wave front incident on the slit should be ............

Two beads, each with charge $q$ and mass $m$, are on a horizontal, frictionless, non-conducting, circular hoop of radius $R$. One of the beads is glued to the hoop at some point, while the other one performs small oscillations about its equilibrium position along the hoop. The square of the angular frequency of the small oscillations is given by [ $\varepsilon_0$ is the permittivity of free space.]

There are two equipotential surface as shown in figure. The distance between them is r. The charge of –q coulomb is taken from the surface A to B, the resultant work done will be