During the propagation of electromagnetic waves in a medium:
Electric energy density is equal to the magnetic energy density.
Both electric and magnetic energy densities are zero.
Electric energy density is double of the magnetic energy density.
Electric energy density is double of the magnetic energy density.
An electromagnetic wave in vaccum has the electric and magnetic fields and which are always perpendicular to each other. the direction of polarisation is given by and that of wave propagation by then
The threshold frequency for a metallic surface corresponds to an energy of 6.2 eV, and the stopping potential for a radiation incident on this surface 5 V. The incident radiation lies in
X-ray region
ultra-violet region
infra-red region
infra-red region
The direction of propagation of electromagnetic wave is along
Electric field vector, E
Magnetic field vector, B
E . B
E × B
Assume that a radio station is about 200 km away at your location and the station operates 972 kHz. How long does it take for an electromagnetic signal to travel from the station to you and how many wave crests does it send out per second ?
666 µs and 9.72 × 10^{5} crests per second
666 µs and 972 × 10^{5} crests per second
555 µs and 97.2 × 10^{7} crests per second
555 µs and 0.972 × 10^{5} crests per second
The electric field portion of an electromagnetic wave is given by (all variables in SI units) E = 10^{-4} sin(6 x 10^{5} t − 0.01 x). The frequency (f) and the speed (v) of electromagnetic wave are
f = 30/π kHz and v = 1.5 × 10^{7} m/s
f = 90/π kHz and v = 6.0 × 10^{7} m/s
f = 300/π kHz and v = 6.0 × 10^{7} m/s
f = 600/π kHz and v = 7.5 × 10^{7} m/s
If the directions of electric and magnetic field vectors of a plane electromagnetic wave are along positive y- direction and positive z-direction respectively, then the direction of propagation of the wave is along
positive z-direction
negative z-direction
negative y-direction
positive x-direction
The amplitudes E_{0} and B_{0} of electric and the magnetic component of an electromagnetic wave respectively are related to the velocity c in vacuum as
${\mathrm{E}}_{0}{\mathrm{B}}_{0}=\frac{1}{\mathrm{c}}$
${\mathrm{E}}_{0}=\frac{\mathrm{c}}{{\mathrm{B}}_{0}}$
B_{0} = cE_{0}
E_{0} = cB_{0}
Identify the mismatched pair.
Microwaves — Aircraft navigation
Radio waves — Cellular phone
γ rays — Klystron
Ultraviolet rays — LASIK