Power in Circuits Video Lessons

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Problem: The circuit shown has four identical light bulbs and an ideal batterya. Rank the brightness of the bulbs. Explain your reasoning.b. A wire is now added to the circuit as shown.i. Does the brightness of bulb C increase, decrease or remain the same? Explain your reasoning.ii. Does the brightness of bulb A increase, decrease, or remain the same? Explain.iii. Does the current through the battery increase, decrease, or the remain the same? Explain.

FREE Expert Solution

a.

Since all the bulbs are identical, we take the resistance of each bulb to be R.

Power is expressed as:

P=i2R

From this equation, the current is directly proportional to power. 

Ohm's law:

i=VR

We need to determine the current flowing in each branch. 

Let's re-label the figure as below. 

The currents are drawn based on Kirchhoff's junction rule.

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Problem Details

The circuit shown has four identical light bulbs and an ideal battery
a. Rank the brightness of the bulbs. Explain your reasoning.

b. A wire is now added to the circuit as shown.

i. Does the brightness of bulb C increase, decrease or remain the same? Explain your reasoning.ii. Does the brightness of bulb A increase, decrease, or remain the same? Explain.
iii. Does the current through the battery increase, decrease, or the remain the same? Explain.

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What scientific concept do you need to know in order to solve this problem?

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Based on our data, we think this problem is relevant for Professor Castano's class at NSU.