A hypothesis is a proven scientific fact.

Water expands when heated at all temperatures.

Objects in free fall accelerate at different rates independent of their mass.

The Bohr model predicts that electrons occupy discrete orbits.  

Magnetic fields can exert forces on moving charges.  

The exponent in scientific notation represents the number of significant figures.

The boiling point of water increases with pressure.

The Doppler effect applies to both sound and light waves. 

The focal length of a lens is the distance from the lens to the image.  

Ultrasound frequencies are below 20 kHz and can be heard by humans.