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Current VS Heat.

Discussion in 'General Electronics Discussion' started by cjdelphi, Jan 20, 2012.

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  1. cjdelphi

    cjdelphi

    1,096
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    Oct 26, 2011
    I was trying to visualize this in my head and it made no sense..... the simplest circuit imaginable, a 10 watt resistor connected between + - of a 5v regulated power supply, the resistor value let's say 5 ohms...

    We now have 1 amp running through this circuit, now here's the question lol.. I Take a wire I snip off a meter's worth I strip the plastic off and I'm left with 20 - 30 individual strands of copper wire, I connect a single strand of copper wire between + of the regulator/battery whatever to the Resistor

    [+] ~~~~ (1 strand of wire)~~~~~~--------- [5ohm Resistor]-----------------------------[ - ]


    That single strand of wire will get hot enough to melt plastic. Add, 10 or so more strands of wire, and then run the circuit, the wire no longer gets hot, it stays cool and does not melt the plastic...

    Why?
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,475
    2,820
    Jan 21, 2010
    Go back and read the thread on resistance that you started some time ago.

    Multiple strands in parallel have less resistance than a single strand so less power is dissipated.

    Alternatively you could see the issue as each strand having the same resistance, but now each one carries less current and therefore dissipates far less power (it is proportional to the square of current)

    Another factor is that the 10 strands of wire will have far more surface area than a single wire (ten times), so the power dissipated is reduced by 90% and the area to radiate that power is increased by a factor of 10.
     
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