Power PLEASE Help Test THURSDAY

  • Thread starter Thread starter BuBbLeS01
  • Start date Start date
  • Tags Tags
    Power Test
Click For Summary
SUMMARY

The discussion centers on the confusion surrounding power equations for electrical circuits, specifically when calculating the power dissipated by light bulbs in series. The participant correctly identifies the equations P = IV, P = I²R, and P = V²/R but struggles with their application. In the case of two 97 W light bulbs connected in series to a 114 V supply, the correct approach involves using P = V²/R to find the power dissipated by each bulb, resulting in 24.3 W per bulb, rather than simply doubling the rated power. Understanding the reduction of current in series circuits is crucial for accurate calculations.

PREREQUISITES
  • Understanding of Ohm's Law (V = IR)
  • Familiarity with electrical power formulas (P = IV, P = I²R, P = V²/R)
  • Basic knowledge of series circuits and current behavior
  • Ability to calculate resistance from power ratings and voltage
NEXT STEPS
  • Study the principles of series and parallel circuits in electrical engineering
  • Learn how to calculate equivalent resistance in series circuits
  • Explore the concept of power distribution in electrical systems
  • Review practical examples of power calculations in real-world applications
USEFUL FOR

Students preparing for electrical engineering exams, educators teaching circuit theory, and anyone seeking to deepen their understanding of electrical power calculations.

BuBbLeS01
Messages
602
Reaction score
0
Power...PLEASE Help...Test THURSDAY!

I am having a hard time understanding why some power equations for finding the power dissipated by light bulb(s) don't work. I have...
P = IV = I^2R = V^2/R
But for some of the problems these equations are getting me different numbers for each one! I am getting confused and I now don't know when to use which one and I have a test on Thursday! One example...

Two 97 W (114 V) lightbulbs are wired in series, then the combination is connected to a 114 V supply. How much power is dissipated by each bulb?

I found I using P/V = .851 then when I go to find the power the only equation that gets me the right answer is P = V^2/R then divide by 2 = 24.3 W
 
Physics news on Phys.org
The current reduces through each when connected in series, so that the power is not just 2*97 W. You have to find the V across each or find I.
 

Similar threads

Graphing the Power dissipated in a resistor
  • · Replies 1 ·
Replies
1
Views
2K
Power calculations of AC signal
  • · Replies 1 ·
Replies
1
Views
2K
Power Line Losses: Trivial Problem, Confusing Answer
  • · Replies 9 ·
Replies
9
Views
2K
How to find the power consumed by the light bulb
  • · Replies 19 ·
Replies
19
Views
3K
Long distance electrical transmission efficiency
  • · Replies 2 ·
Replies
2
Views
2K
Semiconductor surface engineering
  • · Replies 3 ·
Replies
3
Views
803
Which of the bulbs glow brightest and least bright?
  • · Replies 8 ·
Replies
8
Views
3K
What Is the EMF of a Cell with Given Energy Dissipation and Current?
  • · Replies 4 ·
Replies
4
Views
5K
Problem: How can American 110V light bulbs be used on a 240V grid?
  • · Replies 25 ·
Replies
25
Views
6K
Solving Current & Power in 4 & 3 Wire Circuits
  • · Replies 9 ·
Replies
9
Views
2K