RE-NEET Physics Electromagnetic Waves Class 12 Questions

An electromagnetic wave travelling in a lossless dielectric medium having a dielectric constant, εᵣ=9, has the electric field, Eₓ=E₀sin (kz^{-2}π×10⁶t) Vm⁻¹ where E₀ is the amplitude and k is the wave vector. Among the following options, the incorrect choice is:

Two infinitely long parallel conducting wires A and B carry currents I and 2I, respectively, in the same direction. The wire A has uniform mass per unit length λ and lies on an insulated floor. The wire B is kept fixed at a height h above the floor. The minimum magnitude of h so that the wire A does not rise from the floor is : [g is the acceleration due to gravity and μ₀ is the permeability of free space.]

The following table presents the parts of the electromagnetic spectrum and their corresponding major applications.

A current I₀ flows through a metallic circular loop of radius r as shown in the figure. Resistance of the segment ABC is half that of ADC. Magnitude of magnetic field at the center O of the loop is:

Consider a long solenoid of length l and radius r. If n is the number of turns per unit length and μ₀ is the permeability of free space, the inductance of the solenoid is:

The electromagnetic radiation which has the smallest wavelength are

If the ratio of relative permeability and relative permittivity of a uniform medium is 1 : 4. The ratio of the magnitudes of electric field intensity (E) to the magnetic field intensity (H) of an EM wave propagating in that medium is