a. Superconductivity
The pairing of electrons in certain materials when cooled below a critical temperature, causing the material to lose all resistance to electricity flow. Superconductors can carry electric current without any energy losses. About one third of all metals loose all electrical resistance at temperatures below a specific critical temperature. Many elemental metals are superconductors. Some critical temperatures are: lead Tc = 7.2 K, tin Tc = 3.7 K, niobium Tc = 9.2 K, aluminum Tc = 1.2 K, mercury Tc = 4.2 K, and vanadium Tc = 5.3 K. Superconducting wires can carry currents with zero losses up to very high current densities. Above a critical current density Jc, superconductivity is supressed. A typical critical current density is 106 A/cm2. Superconductivity is also supressed by strong magnetic fields.
b. Night Vision Technology
Night vision works in the basis of the following two technologies Image enhancement - This works by collecting the tiny amounts of light, including the lower portion of the infrared light spectrum, that are present but may be imperceptible to our eyes, and amplifying it to the point that we can easily observe the image. Thermal imaging - This technology operates by capturing the upper portion of the infrared light spectrum, which is emitted as heat by objects instead of simply reflected as light. Hotter objects, such as warm bodies, emit more of this light than cooler objects like trees or buildings.
c. Seismograph
A measuring instrument for detecting and measuring the intensity and direction and duration of movements of the ground (as an earthquake). It senses and records the vibrations that radiate out from the earthquake focus. It is a machine for measuring the intensity of earthquakes by recording the seismic waves that they generate.