Question

An electromagnetic wave of frequency $5GHz$ is travelling in a medium whose relative electric permittivity and relative magnetic permeability both are $2.$ Its velocity in this medium is $.......\times 10^{7}m/s$

Answer 1

Answer: 15

Given $:f=5GHz$
${ϵ}_r=2$
${\mu }_r=2$
velocity of wave $\Rightarrow v=\frac{c}{n}$ ....... (1)
where, $n=\sqrt{{\mu }_r{ϵ}_r}$ and $c=$ speed of light $=3\times 10^{8}m/s$
$n=\sqrt{2\times 2}=2$
put the value of $n$ in we get
$\Rightarrow v=\frac{3\times 10^8}{2}=15\times 10^{7}m/s$
$\Rightarrow X\times 10^7=15\times 10^7$
$X=15$