Two identical 6 Ω bulbs are connected to a 12 V battery, first in series and then in parallel. Calculate how many times greater the current drawn from the battery is in the parallel arrangement.

Electromagnetism Challenge #2 — Series & Parallel

Series versus
parallel bulbs.

Electromagnetism Medium

Problem

Two identical 6 Ω bulbs are connected to a 12 V battery — first in series, then in parallel. How many times greater is the current drawn from the battery in the parallel arrangement?

Bulb resistance\( R = 6\ \Omega \) each
Battery voltage\( V = 12\ \mathrm{V} \)
Arrangementsseries, then parallel
Answer asa ratio (×)

Ignore internal resistance; the bulbs behave as fixed resistors.

Hint: work each circuit separately. Series: resistances add. Parallel: two equal resistors halve. Find the battery current in each case with \( I = \tfrac{V}{R} \) — then compare.

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Series versusparallel bulbs.

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Series versus
parallel bulbs.