} Jerry Kaidor writes:
} >Roger Garnett [me] writes:
} >>(Don't use 125/250V fuses in your car- they are designed differently)
} > What's the difference? Seems to me that 10 Amps is 10 amps,
} Don Tsang:
} Uhh... ever stick a 12 volt power supply on a 3 volt lightbulb?
} 10 Amps is 1250 watts at 125 volts. If the resistance on the fuse
} is, say, .1% of the total resistance on the circuit, we're talking
} a 1.25 watt lightbulb, equivalent to about 400 mA @ 3 volts.
[etc.]
Jerry:
} ---- No, the system voltage is NOT across the fuse. The only voltage
} across the fuse is that caused by the current through the fuse going through
} the resistance of the fuse V = IR. The power dissipated by the fuse is I*I*R.
^^^^^^^^^^^^^^^^^^^^^^^^^^
} This power dissipated by the fuse is totally independant of the system
} voltage. It is determined TOTALLY by the CURRENT through the fuse!
You've almost got it! Fuses are indeed a resistance type device, and it's
*really* a certain power level which makes them burn out, not just current.
The 32 volt automotive fuses are designed to have a lower resistance, so
as not to drop as much voltage accross them. Take a look at some
125/250 V fuses, and some 32 V fuses. Note the much more massive fuse
link in the 32V fuse. Think about it. (hint- lower resistance -> lower power)
I'll let you do your own math.
________
/___ _ \ Roger Garnett (garnett@BATCOMPUTER.TN.CORNELL.EDU)
/| || \ \ Agricultural Economics |
| |___|| _ | 3 Warren Hall | South Lansing Centre For
| | \ | | | Cornell University | Wayward Sports Cars
\| \ |__/ / Ithaca, N.Y. 14853 | (607) 533-7735
\________/ (607) 255-2522 | SAFETY FAST!
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