For a particle in a periodic potential where vx) v(x+d), is the of motion? (the eigenstates have the form of momentum constant a etsu(z), where u)-u(+ how about hk?

Sorry i don’t know what to do

Answerit decreases;

Sounds propagates through some kind of medium. usually it's air, but it goes just as well through solid objects like walls, windows etc. a soundwave will compress the (air)molecules in front of it, and if this increased density wave hits your ears, you register it as sound. solid objects like walls are a lot denser than air, this means that they will damp a wave, but also carry it easier.