Re: [Phys-l] cars and physics

[Bernard Cleyet <bernardcleyet@redshift.com>]

On 2011, Feb 21, , at 12:46, Quist, Oren wrote:

> I was told this, but never verified it.
>
> One reason cars switched from 6-volt to 12-volt (when I started driving, most cars were 6-volt) was that the time constant to charge up the condenser (what we call the capacitor) was too long to effectively fire eight spark plugs at normal rpm speeds.  As V-8's became popular, the 12-volts became necessary.  Of course the time constant would not change as the voltage went up, but double the voltage would lead to double the charge which was then enough to fire the plugs.  
>
> True or false???   -- whatever, it makes for an interesting calculation.

And I always thought the cap. was too protect the points (switch on opening), and to collapse the mag. field in the "coil" faster.

bc disbused.