As water pressure changes, the volume of air in a bladder. pressure tank contracts and expands. Periodically, the amount. of air in the tank should be measured and the tank recharged if. the air is too low. Bladder pressure tanks do not provide any. useful water storage capacity.
Add Image. Exotic Materials are the strange and unusual elements produced by science, nature, or some strange alien force. Such materials could be alloys, isotopes, chemicals, and such.
Hard Magnetic Materials. Soft Magnetic Materials. 1. Materials which retain their magnetism and are difficult to demagnetize are called hard magnetic materials. These materials retain their magnetism even after the removal of the applied magnetic field. Hence these materials are used for making permanent magnets.n permanent magnets the movement of the domain wall is prevented. They are prepared by heating the magnetic materials to the required temperature and then quenching them. Impurities increase the strength of hard magnetic materials. Soft magnetic materials are easy to magnetize and demagnetize.