Question

A wave has wavelength $50A^o$. State the speed of wave in vacuum.

• A. $3\times {10}^{8}m{s}^{-1}$
• B. >$3\times {10}^{8}m{s}^{-1}$
• C. <$3\times {10}^{8}m{s}^{-1}$
• D. Insufficient information

Answer 1

The correct option is A $3\times {10}^{8}m{s}^{-1}$

X-rays has a wavelength of $50A^o$.
All electromagnetic radiation, of which radio waves and X-rays are examples, travels at the velocity of light, in a vacuum. The only difference between the two is that the frequency of X-rays is very much higher than radio waves.
Hence, X-rays travels at a speed of ${3\times 10}^{8}m/s$.