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7
MCQ (Single Correct Answer)

An EM wave radiates outwards from a dipole antenna, with $E_o$ as the amplitude of its electric field vector. The electric field $E_o$ which transports significant energy from the source falls off as

A
$\frac{1}{r^3}$
B
$\frac{1}{r^2}$
C
$\frac{1}{r}$
D
remains constant
8
MCQ (Single Correct Answer)

An electromagnetic wave travels in vacuum along $z$-direction $\mathbf{E}=\left(E_1 \hat{\mathbf{i}} E_2 \hat{\mathbf{j}}\right) \cos (k z-\omega t)$. Choose the correct options from the following

A
The associated magnetic field is given as $$\mathbf{B}=\frac{1}{C}\left(E_1 \hat{\mathbf{i}}-E_2 \hat{\mathbf{j}}\right) \cos (k z-\omega t)$$
B
The associated magnetic field is given as $$\mathbf{B}=\frac{1}{C}\left(E_1 \hat{\mathbf{i}}-E_2 \hat{\mathbf{j}}\right) \cos (k z-\omega t)$$
C
The given electromagnetic field is circularly polarised
D
The given electromagnetic wave is plane polarised
9
MCQ (Multiple Correct Answer)

An electromagnetic wave travelling along $z$-axis is given as $\mathbf{E}=\mathbf{E}_{\mathbf{o}} \cos (k z-\omega t)$. Choose the correct options from the following

A
The associated magnetic field is given as $B=\frac{1}{C} \hat{\mathbf{k}} \times \mathbf{E}=\frac{1}{\omega}(\hat{\mathbf{k}} \times \mathbf{E})$
B
The electromagnetic field can be written in terms of the associated magnetic field as $\mathbf{E}=c(\mathbf{B} \times \hat{\mathbf{k}})$
C
$\hat{\mathbf{k}} \cdot \mathbf{E}=0, \hat{\mathbf{k}} \cdot \mathbf{B}=0$
D
$\hat{\mathbf{k}} \times \mathbf{E}=0, \hat{\mathbf{k}} \times \mathbf{B}=0$
10
MCQ (Multiple Correct Answer)

A plane electromagnetic wave propagating along $x$-direction can have the following pairs of $\mathbf{E}$ and $\mathbf{B}$.

A
$E_x, B_y$
B
$E_y, B_z$
C
$B_{x^{\prime}} E_y$
D
$E_z, B_y$
11
MCQ (Multiple Correct Answer)

A charged particle oscillates about its mean equilibrium position with a frequency of $10^9 \mathrm{~Hz}$. The electromagnetic waves produced

A
will have frequency of $10^9 \mathrm{~Hz}$
B
will have frequency of $2 \times 10^9 \mathrm{~Hz}$
C
will have wavelength of 0.3 m
D
fall in the region of radiowaves
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