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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
12
MCQ (Multiple Correct Answer)

The source of electromagnetic waves can be a charge

A
moving with a constant velocity
B
moving in a circular orbit
C
at rest
D
falling in an electric field
13
MCQ (Multiple Correct Answer)

An EM wave of intensity I falls on a surface kept in vacuum and exerts radiation pressure $p$ on it. Which of the following are true?

A
Radiation pressure is $\frac{I}{\mathrm{C}}$ if the wave is totally absorbed
B
Radiation pressure is $\frac{I}{\mathrm{C}}$ if the wave is totally reflected
C
Radiation pressure is $\frac{2 I}{\mathrm{c}}$ if the wave is totally reflected
D
Radiation pressure is in the range $\frac{I}{\mathrm{C}}< p<\frac{2 I}{\mathrm{C}}$ for real surfaces
14
Subjective

Why is the orientation of the portable radio with respect to broadcasting station important?

Explanation

The orientation of the portable radio with respect to broadcasting station is important because the electromagnetic waves are plane polarised, so the receiving antenna should be parallel to the vibration of the electric or magnetic field of the wave.

15
Subjective

Why does microwave oven heats up a food item containing water molecules most efficiently?

Explanation

Microwave oven heats up the food items containing water molecules most efficiently because the frequency of microwaves matches the resonant frequency of water molecules.