Potentiometer, an electrical device that measures potential difference between two points in a circuit by comparison with a standard battery of known potential difference. The name is also applied to a variable resistor that provides varying amounts of potential difference.
An invisibility cloak seems perfectly believable in the magical world of Harry Potter, but in the real world, it's impossible, right? Not so fast.
British authorities have found traces of polonium-210 in at least five buildings and three British Airways jets since Alexander Litvinenko fell ill.