Soldering other precipitation may wash the lead into the groundwater. Unfortunately, most lead-free solders are not eutectic formulations, melting at around , making it more difficult to create reliable joints with them. Other common solders include low-temperature formulations (often containing bismuth), which are often used to join previously-soldered assemblies without unsoldering earlier connections, and high-temperature formulations (usually containing silver) which are used for high-temperature operation or for first assembly of items which must not become unsoldered during subsequent operations. Alloying silver with other metals changes the melting point, adhesion and wetting characteristics, and tensile strength. Of all the brazing alloys, silver
Distributed element circuit led to wider applications. Distributed element circuits are those circuits designed using the distributed element model. This model is an alternative to the lumped element model in which the passive electrical elements of electrical resistance, capacitance and inductance are assumed to be "lumped" at one point in space in, respectively, a resistor, capacitor or inductor lumped component. The distributed element model is used when this assumption no longer holds and those quantities are considered to be distributed in space. The assumption breaks down when there is a significant time taken for electromagnetic waves to travel from one terminal of the