Here's way-cool video of lightning strikes filmed in super slow-motion.ģ. (That's why lightning usually looks flickery.) Each stroke lasts about 30 microseconds. A typical lightning strike is about 40 coulombs of charge, typically consisting of four separate "strokes". If 37 coulombs of charge flows down a wire every 7.5 seconds, what is the current? SOLUTIONĢ. (a) 1 milliamp is one-thousandth of an amp, or in other words, 1 A = 1000 mA.ġ. (a) What is that current, in amps? (b) How many electrons is that, per second? An iPod Nano uses about 25 mA of current.ĮXAMPLE An iPod Nano, playing audio only, uses about 25 mA of current.The battery of a car is used to power the small-yet-mighty electric starter motor that turns the engine in order to start it. Car batteries (for an old-fashioned, internal-combustion non-hybrid, non-electric car) typically max out at between 500 and 600 amps.The DVD player connected to my TV at home uses 140 milliamps (0.14 A).Too high a current can cause the wiring to catch fire.) (Circuits breakers are safety devices designed to automatically shut off the current if too much flows. A given circuit in your house, all controlled by a single circuit breaker, can carry a maximum of 15 or 20 amps, depending on the circuit breaker.So, saying that 1 amp is flowing through a wire is equivalent to sayingĦ.24x10 18 electrons are flowing down the wire every second. The unit we use to measure current is the ampere, usually Almost always, the movingĬharges are electrons (NOT protons or other charged particles). Is defined as the rate of charge movement. We'll use the variable I to stand for current. So, we use a larger unit to measure charge, called the coulomb.ĪND NOW, SOME NEW STUFF Usually, in electronics work we aren't dealing with stationary ( static)Ĭharges, but rather moving charge: electrical current. For example, there are typically about 10,000,000,000,000,000Įlectrons per second flowing in the wires of a small, low-power circuit The charge on a single electron is very small - too small to be convenient Protons are likewise identical to each other. All electrons are identical to each other, and all The same magnitude (amount) of charge, although the A QUICK REVIEW OF OLD STUFF Electrons and protons have
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