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sunshine 03 · Aug 20, 2009, 07:31 PM

Hi Everyone
I was once told that a common training tool for exposing electricians to resistance; was a large bulb in series with a small bulb. I believe it was on a 12 volt system and the bottom line is; that no matter what - the small bulb was the only one that worked. And another example would be; 6 light bulbs (2 ohms apiece) in series on a 12 volt circuit - resulting in none of the bulbs illuminating properly. Is anyone aware of these exercises and the resistances used in proportion to volts and amps ?
I really appreciate your time and any ideas.
Thanks

Missouri Bound · Aug 20, 2009, 07:50 PM

Never heard of that exercise... and the first one is incorrect. Both bulbs will light, although one will be dimmer... and what is "illuminating properly"?

KISS · Aug 20, 2009, 08:26 PM

Not so, if one is a headlamp and one is an instrument panel light.

Just won't happen. Only the instrument panel light will light.

The headlamp say draws 15 amps and the instrument lamp say 0.1 Amps. The instrument lamp limits the current.

In fact, a light bulb can be considered a voltage dependent resistor and the resistance of a tungsten bulb is about 15 times less when cold.

Missouri Bound · Aug 20, 2009, 08:48 PM

KISS... I stand corrected. I see now why series circuits are limited to Xmas tree lights.

KISS · Aug 20, 2009, 08:53 PM

Yep and those lights try to fail shorted by design.

You can sit or be in any position and be corrected too. I don't mind.

At least I explained it on the first shot and you got it. I'll admit, I exaggerated big and little a bit.