What are the quantities that remain same during refraction ?

The speed that the wave is traveling changes as it refracts (either increases as it enters a medium with a lower refractive index; or decreases as it enters a medium with a higher refractive index). At the same time, the wavelength changes (increases or decreases proportionally) depending on the change in the wave's velocity.The frequency remains unchanged. The direction also changes.

however it means the same but still i felt to add this that energy of the wave also remains the same as energy = h*f where f is frequency... since freuency remains constant..