All wavelengths of light travel at the same speed in a vacuum. In the vacuum, it is unaffected by the wavelength.
What physical quantity is the same for $X$-rays of wavelength $10^{-10} \mathrm{~m}$, the red light of wavelength $6800 \AA$ and radiowaves of wavelength $\mathbf{5 0 0 m ?}$
What physical quantity is the same for $X$-rays of wavelength $10^{-10} \mathrm{~m}$, the red light of wavelength $6800 \AA$ and radiowaves of wavelength $\mathbf{5 0 0 m ?}$