MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY MARTYN F. CHILLMAID / SCIENCE PHOTO LIBRARY
Balance in a case. A balance measuring the weight of two glass beakers. Balances are used to measure the weight, and therefore mass, of a substance or object. Balances such as the one shown consist of a pivoted horizontal lever (beam, top), with a weighing pan (scale) suspended from each arm (left and right). The unknown mass is placed in one pan, and known masses are added to the other pan until the beam is as level as possible (equilibrium). When the beam is level the weight of the two masses in each pan is the same. This balance is inside a case to prevent air currents from moving the pans and affecting the results.
Model release not required. Property release not required.