Consider the two circuits shown in the figure below in which the lightbulbs and
ID: 2153264 • Letter: C
Question
Consider the two circuits shown in the figure below in which the lightbulbs and batteries are identical. The resistance of each lightbulb is R.
(a) Find the currents in each lightbulb. (Used E for ? and R for R.)
(b) How does the brightness of B compare with that of C? Explain.
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(c) How does the brightness of A compare with that of B and C? Explain.
Explanation / Answer
The formula for current is: i = v / R (* i=current, v=voltage, R=resistance) So for part A, we are given E as the voltage, and the lightbulb with resistance R. Total current in a circuit remains the constant, so we get that: IA = E/R but for IB and IC since we have to lightbulbs we divide each current by 2 and get: IB = E/2R IC = E/2R part B: since they both have the same current and voltage they will also have the same brightness, so B = C Part C. A will be brighter then B and C because it has more current going through it, and the same amount of voltage, therefore it has greater power and will be brighter. So, A > B = C