Need confirmation on lightbulb experiment

Click For Summary
SUMMARY

The forum discussion centers on a light bulb experiment involving the relationship between battery voltage and amp draw, represented by the equation y = 0.08x + 0.14, where x is the number of batteries and y is the amp draw. Initial resistance measured at 1.3 ohms and a calculated resistance of approximately 11.4667 ohms at 5.16V indicate that the light bulb's behavior is non-linear beyond four batteries. The discussion emphasizes that a linear model is inadequate for accurately modeling the bulb's resistance across varying voltages, as detailed in the linked educational resource.

PREREQUISITES
  • Understanding of Ohm's Law
  • Familiarity with linear equations and graphing
  • Basic knowledge of electrical resistance and circuits
  • Experience with digital graphing tools or calculators
NEXT STEPS
  • Research the non-linear characteristics of light bulbs and their resistance behavior
  • Learn how to construct and interpret V vs I curves for electrical components
  • Explore digital tools for graphing equations and analyzing electrical data
  • Investigate advanced modeling techniques for non-ohmic devices
USEFUL FOR

Students, educators, and hobbyists interested in electrical engineering, particularly those conducting experiments with light bulbs and battery circuits.

Flyingwing12
Messages
41
Reaction score
0
I was piddling with my meter and graphing calculator and came up with this equation

y= .08x+.14

This equation uses the number of batteries for X, and the Amp draw through a light bulb for Y.

The results are theoretical past 4 batteries.

The batteries were 1.29 v when the experiment began.

The real question here is about resistance.

Outside here it is about 80 degrees F, the ohmmeter showed 1.3 ohms from the light-bulb. The light bulb, using Ohms law, will have a resistance of ~11.4667 ohms when ~5.16 V are put to it. Meaning an amp draw of ~.45A

*With this initial resistance and final resistance being known, can I use a linear model to find the resistance of the bulb for each individual cell?*

How would this model be constructed?

If a graph were to be constructed it would start at (0,1.3) and end at (4, 11.46667). Is there any digital way of finding the missing values?

Kind of a math question isn't it?
 
Last edited:
Engineering news on Phys.org
See part 2 in this link. It describes exactly your experiment, even uses your method of force voltage with batteries, and how to plot out the v vs i curve and what not.

http://teachers.usd497.org/agleue/unit_pdfs/electricity_unit_1/electricity_unit_1_ohm_laws_and_light_bulb_lab.pdf
 
Last edited by a moderator:
btw, i found this via a google when looking for the v vs i of a light bulb over this voltage range. here the bulb's large signal behavior isn't ohmic so it can't be modeled accurately over this range with an equation of the form y=mx+b.

you'll see all that, and an explanation, in the results section of the link above.
 

Similar threads

  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
97K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 14 ·
Replies
14
Views
5K
  • · Replies 15 ·
Replies
15
Views
11K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 10 ·
Replies
10
Views
6K
  • · Replies 3 ·
Replies
3
Views
3K