Key Terms
- ampere (amp)
- SI unit for current;
- circuit
- complete path that an electrical current travels along
- conventional current
- current that flows through a circuit from the positive terminal of a battery through the circuit to the negative terminal of the battery
- critical temperature
- temperature at which a material reaches superconductivity
- current density
- flow of charge through a cross-sectional area divided by the area
- diode
- nonohmic circuit device that allows current flow in only one direction
- drift velocity
- velocity of a charge as it moves nearly randomly through a conductor, experiencing multiple collisions, averaged over a length of a conductor, whose magnitude is the length of conductor traveled divided by the time it takes for the charges to travel the length
- electrical conductivity
- measure of a material’s ability to conduct or transmit electricity
- electrical current
- rate at which charge flows,
- electrical power
- time rate of change of energy in an electric circuit
- Josephson junction
- junction of two pieces of superconducting material separated by a thin layer of insulating material, which can carry a supercurrent
- Meissner effect
- phenomenon that occurs in a superconducting material where all magnetic fields are expelled
- nonohmic
- type of a material for which Ohm’s law is not valid
- ohm
- unit of electrical resistance,
- Ohm’s law
- empirical relation stating that the current I is proportional to the potential difference V; it is often written as , where R is the resistance
- ohmic
- type of a material for which Ohm’s law is valid, that is, the voltage drop across the device is equal to the current times the resistance
- resistance
- electric property that impedes current; for ohmic materials, it is the ratio of voltage to current,
- resistivity
- intrinsic property of a material, independent of its shape or size, directly proportional to the resistance, denoted by
- schematic
- graphical representation of a circuit using standardized symbols for components and solid lines for the wire connecting the components
- SQUID
- (Superconducting Quantum Interference Device) device that is a very sensitive magnetometer, used to measure extremely subtle magnetic fields
- superconductivity
- phenomenon that occurs in some materials where the resistance goes to exactly zero and all magnetic fields are expelled, which occurs dramatically at some low critical temperature