Metal detectors are electronic machines that can be used to detect the presence of metal. They can penetrate wood, soil and various nonmetallic items. Electromagnetism is the main principle behind the working of metal detectors. The main components of a metal detector are battery case, receiver antenna, electronic box and a transmitter. A magnetic field is created by the transmitter using the power from the battery. This field magnetizes any metal in its presence. The receiver obtains the electromagnetic signature of the metal substance and transmits a signal to the electronic box. Usually, a speaker is used to increase the strength of the signal. The presence of metal is indicated by a beep sound. There are several types of metal detectors available in the market today. Some common types are walk through detectors, coin detectors and underwater detectors. Metal detectors for hunting relics and those that detect the presence of gold are also quite popular.

Ever since its inception in the 1980’s, Mario games have been highly popular among people of all ages. The various Mario games have sold more than 210 million copies. Today, Mario appears in more than 200 games and they cover various genres. In addition to platform games, one can find role playing, puzzles, fighting, sports and racing Mario games. Among the various online games, Mario is the most popular. Today, one can find Mario merchandise such as pens, toys, books and shirts. Mario was created by a Japanese designer. The various games portray Mario as either an Italian or an American. Although Mario is a plumber by profession, his main job is to fight Bowser and save Princess Peach. He is a short and stubby character who resides in Mushroom Kingdom. Recent versions of the game incorporate high end graphics. One can also find all the classic Mario games on several online sites.