Electric Circuits

[lionelsoni]

Yes.

[coaldust2026]

Thanks, Bob.  Am I correct in thinking, then, that two resistors in parallel would discharge a battery approximately twice as fast as one resistor, three in parallel three times as fast as one, etc. ?

[lionelsoni]

The parallel circuit discharges the battery faster.  However, this problem is a little more complicated than you may have intended it to be, because incandescent lamps, while resistors in the short term (the few milliseconds of an alternating transformer voltage), are not resistors in the long term.

A resistor is a component that follows Ohm's law, that is, for which the current and voltage are proportional to each other.  However, the current in an incandescent lamp varies as the .55 power of the voltage, not proportionately.

So when the 1.5-volt lamps are in parallel across the 1.5-volt cell, each draws its rated current, whatever that is.  When you reconnect them in series, each one gets half the voltage (since they are identical).  Whereas a true resistor's current would drop to half in that circumstance, reducing the cell current to one-fourth, each incandescent lamps current drops only to about 68 percent (.5^.55) of the full-voltage rating; so the total current drops to 34 percent, or about one-third of the parallel circuit's current (which was twice the rated current since each lamp was drawing that current from the cell)..

[coaldust2026]

Hi.  I am trying to increase my knowledge of electric circuits and am wondering if someone would help me in comparing the following two circuits:  Each circuit contains two identical 1.5 volt bulbs, exactly the same amount and kind of wire and a fresh 1.5 volt battery.  One circuit has its two bulbs in series and the other has its wired in parallel.  I understand that in the series circuit the resistance is higher(sum of resistances) , the current lower (Ohm's Law) and the bulbs dimmer.  In the parallel circuit the resistance is lower, the current higher and the bulbs brighter. My question is this:  which circuit drains the battery more quickly - the one with higher resistance or the one with higher current- and why?  Or are the two circuits the same in this respect?  P.S. If the battery has to be of higher voltage to make the circuits work, just make them both the same at the beginning. Thanks for your help.