Which of the following statements is incorrect?

  • A
    The ionosphere acts as a $Mirror$ for radio waves.
  • B
    Ionization of gases in the ionosphere is caused by radiation from the Sun and other stars.
  • C
    The ionosphere contains electrons and positive ions.
  • D
    Ionization of gases in the ionosphere is caused by radio waves.

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Similar Questions

In free space,an electromagnetic wave of $3 \; GHz$ frequency strikes an object of size $\frac{\lambda}{100}$,where $\lambda$ is the wavelength of the wave in free space. The phenomenon that occurs is .....

$A$ wave is propagating in a medium of electric dielectric constant $2$ and relative magnetic permeability $50$. The wave impedance of such a medium is.....$ \Omega$

The electric field associated with an electromagnetic wave propagating in a dielectric medium is given by $\vec{E} = 30(2 \hat{x} + \hat{y}) \sin \left[2 \pi \left(5 \times 10^{14} t - \frac{10^7}{3} z\right)\right] \text{V m}^{-1}$. Which of the following option$(s)$ is(are) correct?
[Given: The speed of light in vacuum,$c = 3 \times 10^8 \text{ m s}^{-1}$]
$(A)$ $B_x = -2 \times 10^{-7} \sin \left[2 \pi \left(5 \times 10^{14} t - \frac{10^7}{3} z\right)\right] \text{Wb m}^{-2}$.
$(B)$ $B_y = 2 \times 10^{-7} \sin \left[2 \pi \left(5 \times 10^{14} t - \frac{10^7}{3} z\right)\right] \text{Wb m}^{-2}$.
$(C)$ The wave is polarized in the $xy$-plane with a polarization angle $\theta = \tan^{-1}(0.5)$ with respect to the $x$-axis.
$(D)$ The refractive index of the medium is $2$.

The electric field of a plane polarized electromagnetic wave in free space at time $t = 0$ is given by the expression $\vec E(x,z) = 10\hat j \cos(6x + 8z)$. The magnetic field $\vec B(x,z,t)$ is given by: ($c$ is the velocity of light)

If $\overrightarrow E$ and $\overrightarrow B$ are the electric and magnetic field vectors of electromagnetic waves,then the direction of propagation of the electromagnetic wave is along the direction of:

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