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3
MCQ (Single Correct Answer)

Light with an energy flux of $20 \mathrm{~W} / \mathrm{cm}^2$ falls on a non-reflecting surface at normal incidence. If the surface has an area of $30 \mathrm{~cm}^2$, the total momentum delivered (for complete absorption) during 30 min is

A
$36 \times 10^{-5} \mathrm{~kg}-\mathrm{m} / \mathrm{s}$
B
$36 \times 10^{-4} \mathrm{~kg}-\mathrm{m} / \mathrm{s}$
C
$108 \times 10^4 \mathrm{~kg}-\mathrm{m} / \mathrm{s}$
D
$1.08 \times 10^7 \mathrm{~kg}-\mathrm{m} / \mathrm{s}$
4
MCQ (Single Correct Answer)

The electric field intensity produced by the radiations coming from 100 W bulb at a 3 m distance is $E$. The electric field intensity produced by the radiations coming from 50 W bulb at the same distance is

A
$\frac{E}{2}$
B
$2 E$
C
$\frac{E}{\sqrt{2}}$
D
$\sqrt{2} E$
5
MCQ (Single Correct Answer)

If $\mathbf{E}$ and $\mathbf{B}$ represent electric and magnetic field vectors of the electromagnetic wave, the direction of propagation of electromagnetic wave is along

A
$\mathbf{E}$
B
B
C
$\mathbf{B} \times \mathbf{E}$
D
$\mathbf{E} \times \mathbf{B}$
6
MCQ (Single Correct Answer)

The ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is

A
$\mathrm{c}: 1$
B
$c^2: 1$
C
$1: 1$
D
$\sqrt{C}: 1$
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
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