Understanding the Resistance of a Filament lamp

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.

[wertherellerbrock]

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!

[leeisenberg]

I need a "Cliff Notes" version of this. Thanks for sharing, - take care

[darkook]

This is the best explanation ever... good job sir

[Robertwclarke]

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.

[mariox]

I expected more: some model and approximate formula. I heard about 4th root ?

[SlyerFox]

Has there been a change to this video from before ?

[ytubeleo]

Would be nice to see AC current as well as DC.