Understanding the Resistance of a Filament lamp
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- Опубликовано: 9 сен 2024
- This video investigates the resistance of a filament lamp: looking at the filament lamp itself and also shape of the current / potential difference graph and discovering what this means.
First of all a recap is taken looking at a linear resistor to understand what an Ohmic component is. The current and voltage are measured to establish the relationship between current and voltage and see that there is a linear relationship for this type of component. The plot of current and voltage gives a straight line
Incandescent or filament lamps consist of a very fine coiled wire coil or filament within the glass bulb. When current passes through this filament, it heats up, becoming white hot and giving out light.
These filament lights are very inefficient converting around 5% of the energy that enters them into light. LEDs are now the preferred form of lamp for many situations.
There is an experiment to measure the resistance of the filament lamp using a voltmeter and an ammeter so that the plot of the current and voltage can be seen. This is not a straight line and this means that the resistance of the filament lamp changes with the potential applied.
As the resistance of the filament lamp changes with voltage, it is said to be non-Ohmic.
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Clear and concise! Saved my evening
Thanks for your comment. We try really hard to be clear and concise.
I need a "Cliff Notes" version of this. Thanks for sharing, - take care
This is the best explanation ever... good job sir
I am really glad it was helpful. Thanks for your comment.
This is great! For some time I had been trying to figure out why Ohm's Law calculations just wouldn't match actual circuit measurements, both with AC and DC, and it was driving me crazy! Now I know. Thank you!
I’m really glad the video helped you. Thanks for commenting.
Super video! One thing got me thinking. At the end it is stated that the relationship is simply current/potential. But really effect of the current here is a rise in temperature and its effects on conductivity as stated earlier in the video. So to conclude should it not be ' A Filament Lamp is Non-Ohmic because Temperature Rise caused by Current flow results in an increase in Resistance' ?
Sorry to be nit picking but I'm sure folk will understand based on the explanation in the video. Thanks for doing the video, I know it takes lots of work.
Thanks for your comment. A really interesting way of looking at it. Yes, you are right, the current flowing through the lamp causes the temperature to rise and hence the resistance to change. The point I was making was that a non-ohmic conductor has a non-linear relationship, whatever the cause. Thanks again.
Would be nice to see AC current as well as DC.
Thanks for you comment. I had not used AC because DC showed what I thought needed to be demonstrated, and as younger people may view it, I did not want to encourage the use of high voltage AC. Sorry if we disappointed you.
The behaviour is the same for AC as it is for DC so no benefit in showing it specifically.
Has there been a change to this video from before ?
Yes, it is the same as before bar a small change we needed to make.
@@ElectronicsNotes May I ask what the change was ?
I expected more: some model and approximate formula. I heard about 4th root ?
Sorry we disappointed, but the video was aimed being an introduction and I didn't want to confuse the issue by adding too much additional detail that would detract from the main concept.
ahhh now i know, thanks a lot ughh
Glad to have helped.
Nice pronunciation.
Thanks