Question

The velocity of an electromagnetic wave in vacuum can be changed by changing

• A. frequency
• B. amplitude
• C. wavelength
• D. None of these

Answer 1

Answer: (D)

In free space speed of electromagnetic wave
$c=\frac{1}{\sqrt{{\mu }_0{\epsilon }_0}}=\frac{E_0}{B_0}$
$=3\times 10^{8}m{s}^{-1}$
Thus, the value of electromagnetic wave is constant and cannot be changed by changing any of the given factors.