Here we show eight standard instructional #48 and #14 bulbs from the Modeling and CASTLE physics curricula connected in parallel with two D cells using typical inexpensive alligator leads whose resistances are ~ 0.09 Ω /wire. The central photos are for reference purposes in regular light, and the outer photos and tables show relative brightnesses, measured voltage drops, and currents with calculated resistances for each adjacent bulb. Final table entries show the voltage drop and current through the battery.
The far lefthand circuit is constructed with #48 (a.k.a. long) high resistance bulbs, whose resistance is about 350 times greater than any single lead, so Rlong >> Rleads, and the circuit is pedagogically well behaved. The far righthand circuit is constructed with #14 (a.k.a. round) low resistance bulbs, whose resistance is only 60 times greater than any single lead, so R16leads becomes comparable with Rround,...