Question

A radio wave of frequency $90MHz$ (FM) enter into a ferrite rod. If ${\epsilon }_r={10}^3$ and ${\mu }_r=10$, then the velocity and wavelength radio wave in ferrite rod is:

• A. $3\times {10}^6{ms}^{-1},3.33\times {10}^{-2}m$
• B. $3\times {10}^5{ms}^{-1},3.33\times {10}^{-1}m$
• C. $3\times {10}^6{ms}^{-1},3.33\times {10}^{-3}m$
• D. $3\times {10}^5{ms}^{-1},3.33\times {10}^{-2}m$

Answer 1

The correct option is A $3\times {10}^6{ms}^{-1},3.33\times {10}^{-2}m$

Velocity of radio wave in ferrite rod: $v=\frac{c}{\sqrt{{ϵ}_r{\mu }_r}}=\frac{3\times {10}^8}{{10}^2}=3\times {10}^{6}m/s$
Wavelength $\lambda =\frac{3\times {10}^6}{90\times {10}^6}=0.333\times {10}^{-1}m=3.33\times {10}^{-2}m$