The derivation for the speed of electromagnetic waves comes out of Maxwell\'s eq
ID: 1387716 • Letter: T
Question
The derivation for the speed of electromagnetic waves comes out of Maxwell's equations for electromagnetism. For this reason, the speed of an electromagnetic wave depends on electromagnetic constants. v = 1 / . (Note: the speed of an electromagnetic wave in vacuum is given the variable c. Some books highlight the equation c = 1 / , which is just a special case of this general equation in vacuum.) In a vacuum, epsilon = epsilon 0 = 8.85 Times 10-12 C2 / Nm2 and mu = mu 0 = 4 pi Times 10-7Tm / A. Calculate the speed of an electromagnetic wave in vacuum. In water, an electromagnetic wave has frequency 5 Times 1015 Hz and wavelength 45 nm . By what factor is the speed of this electromagnetic wave slower than the speed of an electromagnetic wave in vacuum? In glass, an electromagnetic wave has frequency 5 Times 1015 Hz and wavelength 40 nm . By what factor is the speed of this electromagnetic wave slower than the speed of an electromagnetic wave in vacuum?Explanation / Answer
a)
v=sqrt(1/mu*epsilon)
=sqrt(1/4*3.14*10-7*8.85*10-12)
=sqrt(8.99*1016)
=3*108m/s
b)
speed of electromagneticwave in water=5*1015*45*10-9
=225*106m/s
speed of electromagneticwave in vaccum=3*108/225*106 speed of electromagneticwave in vaccum
=1.33speed of electromagneticwave in vaccum
c)
speed of electromagneticwave in water=5*1015*40*10-9
=200*106m/s
speed of electromagneticwave in vaccum=3*108/200*106 speed of electromagneticwave in vaccum
=1.5speed of electromagneticwave in vaccum