user: What is electric current and how is it measured?

assistant: <think>
The movement of electric charge is known as an electric current, the intensity of which is usually measured in amperes. Current can consist of any moving charged particles; most commonly these are electrons, but any charge in motion constitutes a current. Electric current can flow through some things, electrical conductors, but will not flow through an electrical insulator.
By historical convention, a positive current is defined as having the same direction of flow as any positive charge it contains, or to flow from the most positive part of a circuit to the most negative part. Current defined in this manner is called conventional current. The motion of negatively charged electrons around an electric circuit, one of the most familiar forms of current, is thus deemed positive in the opposite direction to that of the electrons. However, depending on the conditions, an electric current can consist of a flow of charged particles in either direction, or even in both directions at once. The positive-to-negative convention is widely used to simplify this situation.
The process by which electric current passes through a material is termed electrical conduction, and its nature varies with that of the charged particles and the material through which they are travelling. Examples of electric currents include metallic conduction, where electrons flow through a conductor such as metal, and electrolysis, where ions (charged atoms) flow through liquids, or through plasmas such as electrical sparks. While the particles themselves can move quite slowly, sometimes with an average drift velocity only fractions of a millimetre per second, the electric field that drives them itself propagates at close to the speed of light, enabling electrical signals to pass rapidly along wires.
In engineering or household applications, current is often described as being either direct current (DC) or alternating current (AC). These terms refer to how the current varies in time. Direct current, as produced by example from a battery and required by most electronic devices, is a unidirectional flow from the positive part of a circuit to the negative.  If, as is most common, this flow is carried by electrons, they will be travelling in the opposite direction. Alternating current is any current that reverses direction repeatedly; almost always this takes the form of a sine wave. Alternating current thus pulses back and forth within a conductor without the charge moving any net distance over time. The time-averaged value of an alternating current is zero, but it delivers energy in first one direction, and then the reverse. Alternating current is affected by electrical properties that are not observed under steady state direct current, such as inductance and capacitance. These properties however can become important when circuitry is subjected to transients, such as when first energised.</think>
The movement of electric charge is known as an electric current, the intensity of which is usually measured in amperes.

user: What does W stand for in the name W. Rex Black?

assistant: <think>
Wilford Rex Black (January 31, 1920 – December 12, 2012) was an American politician.

Wilford Rex Black represented the 2nd Utah Senate District from 1973 to 1997. W. Rex Black, as he was often referred to, was a member of the Democratic party and represented the party as the Minority leader in the Utah Senate for many years.</think>
Wilford

user: What outfit should I wear when traveling to San Francisco in May?

assistant: The weather in San Francisco tends to vacillate between cool and warm temperatures. In order to dress appropriately and be comfortable all day, you should dress in layers. Start with a good pair of jeans, a t-shirt and a lightweight sweater. For your outerwear, choose a puffer jacket to add some insulation in case the wind picks up. Finally, San Francisco is best explored on foot, so wear a comfortable pair of sneakers.