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Intro to electricity

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Intro to electricity Electricity I - Charge! Charge - as fundamental to electricity & magnetism as mass is to mechanics Charge is a concept used to quantatively related "particles" to other particles, in terms of how they affect each other - do they attract or repel?  If so, with what force? Charge is represented by letter Q. The basic idea - likes charges repel (- and -, or + and +) and opposite charges attract (+ and -). Charge is measured in units called coulombs (C).  A coulomb is a huge amount of charge, but a typical particle has a tiny amount of charge: - the charge of a proton is 1.6 x 10^-19 C.  Similarly, the charge of an electron is the same number, but negative, by definition (-1.6 x 10^-19 C).  The negative sign distinguishes particles from each other, in terms of whether or not they will attract or repel.  The actual sign is arbitrarily chosen. The charge of a neutron is 0 C, or neutral. But what IS charge? Charge is difficult to define. ...
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Circuits 2

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OK, so about regular circuits: The images represent SERIES CIRCUITS and PARALLEL CIRCUITS. In a  series  circuit, the current is  constant  and is set by the total resistance of the circuit (the sum of the resistors). If you remove one resistor (or light bulb, as in the first image), the current  stops . If the resistors were identical bulbs, having more bulbs would result in dimmer bulbs, since the battery voltage is distributed among them.  Note that the sum of the voltages "over" the bulbs is equal to the total voltage provided by the battery (give or take some minor losses).  Identical bulbs (or resistors) have identical voltages "over" them - 3 identical bulbs connected to a 9-V battery would have roughly 3-V each over them. In  parallel  circuits, current has multiple paths to take, so the total resistance of the circuit is actually LESS than if the resistors were alone or in series with other resistors - see details belo...
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Problems to submit (and practice for test)

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1.  Show how to compute the wavelength of the radio signal 107.9 MHz.  Note that MHz means 'million Hz." 2.  Concert A is defined as 440 Hz.  Find the following frequencies: a.  the next 2 A's that come after this one (one and two octaves above) b.  A#, which is one note immediately after concert A c.  the wavelength of a concert A note.  Assume that the speed of sound is 340 m/s. 3.  An ambulance siren has a 1000 Hz frequency.  Answer the following questions with:  greater than 1000 Hz, equal to 1000 Hz, less than 1000 Hz.  What frequency do the following people hear? a.  ambulance driver b.  person who the ambulance has passed c.  person who the ambulance is approaching d.  driver who is driving in the opposite direction of the ambulance, after the ambulance has passed 4.  What exactly causes refraction? 5.  Draw the rays that result from the Rays below: .
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