Electromagnetic Waves - Electromagnetism - Physics Previous Year Questions

Which of the following has/have zero average value in a plane electromagnetic wave?

The correct arrangement in increasing order of wavelength of X-rays, UV rays, microwave is

Which of the following waves are used to treatment of muscles ache?

A 30 mW laser beam has a cross-sectional area of 15 mm². The magnitude of the maximum electric field in this electromagnetic wave is given by

[Permuittivity of space, \(\varepsilon_0=9\times10^{-12}\)

Speed of light, \(c=3\times10^8\) m/s]

Speed of electromagnetic wave in a medium having relative permittivity \(\varepsilon_r\) and relative permeability \(\mu_r\) is (speed of light in air, \(c=3\times10^8\) m/s)

What feature of the infrared waves make it useful for the haze photography?

An electromagnetic wave of frequency \(3 \mathrm{~MHz}\) passes from vacuum into a dielectric medium \((\mu_r=1)\) of relative permittivity 4.0. Then,

Column - I lists the waves of the electromagnetic spectrum. Column - II gives approximate frequency range of these waves. Match Column - I and Column - II and choose the correct match from the given choices.

The ratio of amplitude of magnetic field to the amplitude of electric field of an electromagnetic wave propagating in vacuum is

A plane electromagnetic wave of frequency \(20 \mathrm{~MHz}\) travels through a space along \(x\)-direction. If the electric field vector at a certain point in space is \(6 \mathrm{~Vm}^{-1}\), then what is the magnetic field vector at that point?

Which of the following is incorrect for displacement current

A. Displacement current exists only when electric field changes with time

B. Displacement current obeys ohm's law

C. Displacement current produces magnetic field just like conduction current

D. Unlike conduction current, displacement current does not involve the flow of electrons through a conductor