Irodov Solutions → Oscillations and waves → Electromagnetic Waves. Radiation 
4.189. An electromagnetic wave of frequency ν = 3.0 MHz passes from vacuum into a nonmagnetic medium with permittivity ε = 4.0. Find the increment of its wavelength.
4.191. A plane electromagnetic wave of frequency ν = 10 MHz propagates in a poorly conducting medium with conductivity σ = 10 mS/m and permittivity ε = 9. Find the ratio of amplitudes of conduction and displacement current densities.
4.192. A plane electromagnetic wave E = E_{m} cos(ωt  kr) propagates in vacuum. Assuming the vectors E_{m} and k to be known, find the vector H as a function of time t at the point with radius vector r = 0.
4.193. A plane electromagnetic wave E = E_{m} cos(ωt  kr), where E_{m} = E_{m}e_{y}, k = ke_{x}, e_{x}, e_{y} are the unit vectors of the x, y axes, propagates in vacuum. Find the vector H at the point with radius vector r = xe_{x} at the moment
4.196. Find the mean Poynting vector <S> of a plane electromagnetic wave E = E_{m} cos(ωt  kr) if the wave propagates in vacuum.
4.199. A standing electromagnetic wave with electric component E = E_{m} cos kx * cos ωt is sustained along the x axis in vacuum. Find the magnetic component of the wave B(x, t). Draw the approximate distribution pattern of the wave's electric and magnetic components (E and B) at the moments t = 0 and t = T/4, where T is the oscillation period.
4.201. A parallelplate air capacitor whose electrodes are shaped as discs of radius R = 6.0 cm is connected to a source of an alternating sinusoidal voltage with frequency ω = 1000 s^{1}. Find the ratio of peak values of magnetic and electric energies within the capacitor.
4.202. An alternating sinusoidal current of frequency ω = 1000 s^{1} flows in the winding of a straight solenoid whose crosssectional radius is equal to R = 6.0 cm. Find the ratio of peak values of electric and magnetic energies within the solenoid.
4.207. Fig. 4.39 illustrates a segment of a double line carrying direct current whose direction is indicated by the arrows. Taking into account that the potential φ_{2} > φ_{1}, and making use of the Poynting vector, establish on which side (left or right) the source of the current is located.
4.209. A source of ac voltage V = V_{0} cos ωt delivers energy to a consumer by means of a long straight coaxial cable with negligible active resistance. The current in the circuit varies as I = I_{0} cos (ωt  φ). Find the timeaveraged energy flux through the crosssection of the cable. The sheath is thin.
4.212. Find the mean radiation power of an electron performing harmonic oscillations with amplitude a = 0.10 nm and frequency ω = 6.5*10^{14} s^{1}.
