Physics

Large transformers, when used for some time, become very hot and are cooled by circulating oil. The heating of the transformer is due to both the heating effect of current and hysteresis loss.

In classical electromagnetism, magneti-zation or magnetic polari-zation is the vector field that expresses the density of permanent or induced magnetic dipole moments in a magnetic material. The origin of the magnetic moments responsible for magnetization can be either microscopic electric currents resulting from the motion of electrons in atoms, or the spin of the electrons or the nuclei. In the process of magnetization of a bar, the entire bulk of the bar gets magnetized. The magnetization of a material is done by electric current. By the process of magnetization, the formed pieces develop North polarity on one end or side and South polarity on the other end or side, in a very short period of time.

When an unbalanced force acts on an object it causes change in motion of the object, the speed and direction of the object changes and the object moves.

The phenomenon of rise or fall of liquid in a capillary tube is called capillarity. Oil rises through a wick due to capillarity. The narrow pores in the threads of a wick act like tiny capillaries, through which oil rises. Capillary action is the result of adhesion and surface tension.