Magnetostriction effect:

Magnetostriction effect is the property of a ferromagnetic materials (iron, nickel) that causes them to change their shape and dimensions when they are kept in a magnetic field.

Magnetostriction generator which is used for production of ultrasonic waves is based on this principle. This effect causes losses due to frictional heating in susceptible ferromagnetic cores.

This effect is also responsible for high pitched sound coming from the transformers.

Magnetostrictive materials can convert magnetic energy into kinetic energy, or reverse and this property is used to build actuators and sensors.

Piezoelectric effect:

When crystals like quartz or tourmaline are stressed along any pair of opposite faces, electric charges of opposite polarity are induced in the opposite faces perpendicular to the stress. This is known as piezoelectric effect.

In other words the crystals which acquire a charge when compressed, or twisted are said to be piezoelectric. The piezoelectric effect is shown.