How to Determine the Brightness of Bulbs in a New Configuration?

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SUMMARY

The discussion focuses on calculating the brightness of bulbs "g" and "h" in a new electrical configuration using the formulas for power. The participant correctly identifies that the brightness is proportional to power, applying the formula P = V²/R for bulb "g," which receives 2V, indicating it will be brighter than normal. For bulb "h," receiving voltage V, the brightness remains normal. The participant questions the validity of relying solely on one formula, but the consensus is that using P = V²/R is acceptable if applied correctly.

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  • Understanding of electrical power calculations
  • Familiarity with Ohm's Law
  • Knowledge of voltage, current, and resistance relationships
  • Basic concepts of brightness in electrical circuits
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Homework Statement



See attachment
The question asks to calculate the brightness of the bulbs(g and h) in this new configuration.


Homework Equations



Since brightness [itex]\propto[/itex] Power

P= [itex]V^{2}[/itex]/R
P= [itex]I^{2}[/itex]R
E.M.F of One cell : V

The Attempt at a Solution



I used the equation P = V^(2)/R

Since the Voltage across "g" will be 2V and its Resistance is exactly the same as in the reference Attachment, "g" will be brighter than normal.
Similarly, since the Voltage across "h" is going to be V, "h" must be of normal brightness.

I am not sure if my answers make sense since if we apply the 2nd formula : P=R*I^2
we would get a different set of results .

Is it O.K to just rely on one of the two formulas and deduce the final answer based on say P=V^(2)/R ? Would the answers be authentic ?
 

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hms.tech said:
I am not sure if my answers make sense since if we apply the 2nd formula : P=R*I^2
we would get a different set of results .
Not if you do it correctly. Pls post your working.
 

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