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Homework Help: Voltage and the usage of the word

  1. Nov 5, 2004 #1
    here's the question: "which will do more damage, connection a 110 volt appliance into a 220 volt circuit or plugging a 220 volt appliance into a 100 volt circuit?"

    as i understand it, voltage is the "pressure" that creates current flow. voltage is caused by the potential difference between poles. voltage does not, however, flow ion a circuit, but is instead the cause of flowing. please correct me if i am wrong...

    but before i can answer the question, what does it mean to say that an appliance is 100-V? the appliance isn't creating voltage? or is this the trick in a trick question?
  2. jcsd
  3. Nov 5, 2004 #2
    this means that the appliance has been designed to operate with a 110V source voltage

    approximate a simple appliance as a black box resistor (consider a toaster which is just one big resistor). By Ohm's law, our simple appliance will draw a certain amount of current (I = E/R), and dissipate a certain amount of power (P=IR^2).

    If our appliance is designed for 110V power, it is designed to handle a certain amount of current and power dissipation. Plug it into a 220V power supply and all of a sudden it's current draw doubles and has to dissipate twice as much power.

    All that extra current will either blow our simple appliance's fuse (and hopefully protect the internal bits), or fry all the electrical components.
  4. Nov 5, 2004 #3
    thanks for the reply, it was an obvious answer. i need to quit looking for trick questions and just answer. the metaphor of thinking of voltage as pressure seems to hold up; too much pressure and it pops. so, if there is not enough voltage, the current will trickle? and by trickling, i assume this means not enough charge to power up the appliance?
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