a shower of rain drops

a plane mirror

a convex lens

a combination of a convex lens and a concave lens

gravitational potential energy $$\to$$ heat energy to air $$\to$$ kinetic energy $$\to$$ heat energy to ground and apple $$\to$$ sound energy

gravitational potential energy $$\to$$ sound energy $$\to$$ kinetic energy $$\to$$heat energy to air $$\to$$ heat energy to ground and apple

gravitational potential energy $$\to$$ kinetic energy $$\to$$ heat energy to air $$\to$$ heat energy to ground and apple $$\to$$sound energy

gravitational potential energy $$\to$$kinetic energy $$\to$$ sound energy $$\to$$ heat energy to air $$\to$$ heat energy to ground and apple

Bauxite

Quartz

Feldspar

Pitchblende

Current electricity

Static electricity

Magnetic field

Gravitational field