The study of physics, involving matter, energy and motion, includes a laboratory setting where the various principles can be explained through the use of certain instruments and apparatus. Those devices, many of which are common to a physics laboratory, allow an instructor, student or scientist the opportunity to learn and test the basic ideas of physics.
The barometer traces its history to 1643 and Evangelista Torricelli, who discovered the principle of determining atmospheric pressure. The basic Torricelli barometer consists of a long tube filled with mercury. The height of the mercury in the column becomes the medium for measuring atmospheric pressure, with 30 inches at sea level the standard. As the air pressure increases the mercury in the tube will rise, and conversely, as the air pressure falls the mercury will fall. Barometers are very useful in weather prediction with the term barometric pressure a standard on weather forecasts.
An ammeter, the device used by electricians to measure electric current, displays its results in amperes, or amps. Sometimes called an amp meter, its purpose is to identify constant current at a fixed point. It must be fixed or connected in series with a low resistor in order to obtain an accurate reading. In a physics laboratory, ammeters demonstrate electrical current along with voltmeters, ohmmeters and galvanometers.
An apparatus for very precise measurements, a vernier caliper provides the physics laboratory with an instrument to measure the length of an object in lieu of a standard ruler. It can also measure the outer diameter of a cylinder or round object, the inner diameter of a pipe and the depth of a hole.