- #1
FaraDazed
- 347
- 2
Homework Statement
An EM wave with frequency 87Mhz travels in an insulating ferromagnetic material with [itex]\mu_0 \mu_r = 1000[/itex] and [itex]\epsilon_0 \epsilon_r = 10[/itex] - What is the speed of the EM wave in the material.
Homework Equations
[itex]v=(\sqrt{\mu_0 \mu_r \epsilon_0 \epsilon_r})^{-1}[/itex]
The Attempt at a Solution
For part A I am really confused, well kind of, I am wondering whether in the text for part A they made a mistake and it should be just mu_r=1000 and just epsilon_r=10 , instead of the product of them and the constants sub0. Because if I do it as in the question I get a speed of 0.01m/s as shown below.
[itex]
v=\frac{1}{\sqrt{10 \times 1000}} = 0.01 m/s
[/itex]
But if I take it to be the relative values on their own I get a much higher value as shown below.
[itex]
v=\frac{1}{\sqrt{8.85\times 10^{-12} \times 1000 \times 4 \times \pi \times 10^{-7} \times 10 }} = 2.99 \times 10^6 m/s
[/itex]
So my question really, is it possible to have such slow propagating EM waves in materials like that?