great video thanks, reminded me of paul hewitt conceptual physics. he also had a very engaging way to explain complex ideas and make physics fun to learn good memores.
Interesting... additional assumptions... wire will conduct end to end, current/ voltage and amperage the same and not enough to melt or significantly heat the wire..
To do the demonstration, these assumptions are essential! In theory, one can still arrive at the answer without these, of course. Thanks for the comment!
the dot ? is an ratio ,product or multiply ,equaled to is" = " an exact expression , i have read books that have "/" usually the division or fraction of one over the other was used to indicate multiply ,which plays havoc with my habituated model but trees are green sometimes.
Another way to think about it, is to think of a pipe and stretching that pipe to double its length. Water will have a tougher time getting through the stretched pipe, so you know resistance will increase.
Why anybody would find it difficult to answer this, I don't understand. The resistance of wire per unit length (at a sufficiently low frequency to avoid the complication of the skin effect) varies inversely with the cross sectional area. If the wire is stretched to double the length, it halves the cross section area, which means the resistance per unit length must be doubled. However, the resistance of the wire also varies linearly with its length, and as the wire is now twice as long, and has twice the resistance per unit length, it means the overall resistance is quadrupled. Normal caveats apply, such as the cross-sectional area remains constant along the length, the current is low enough that there is no significant heating effect (which increases resistance in metals) and so on.
Students learning about resistance for the first time often struggle with such conceptual questions. Great answers and caveats, though! Spoken like an electrical engineer. Most of our videos are targeted at high school physics teachers to help them 1) engage their students in productive dialogue and 2) develop pedagogical content knowledge (an understanding of student misconceptions, etc)… We will be making and uploading more advanced content early in the new year, so feel free to subscribe and keep an eye out for that!
great video thanks, reminded me of paul hewitt conceptual physics. he also had a very engaging way to explain complex ideas and make physics fun to learn good memores.
Thank you for the nice comment! Paul Hewitt is a great explainer. Lots of nostalgia watching those old videos!
Interesting thanks
Thanks for watching!
Have a look at resistance wire extensometers. Same principle. Useful thing to know.
Good point! This would have been a good real-world application to mention.
As an electrician, I answered this in a few seconds. R goes up as the length goes up.
Very good! Just out of curiosity, did you also intuitively know it would go up by a factor of 4?
Gary Oldman knows math!
😂
Wish this guy was my math teacher 50 yrs ago, I most likely would of passed.
Thank you for watching!
start with 2 resistors in parallel and connect them in series instead
Interesting... additional assumptions... wire will conduct end to end, current/ voltage and amperage the same and not enough to melt or significantly heat the wire..
To do the demonstration, these assumptions are essential! In theory, one can still arrive at the answer without these, of course. Thanks for the comment!
the dot ? is an ratio ,product or multiply ,equaled to is" = " an exact expression , i have read books that have "/" usually the division or fraction of one over the other was used to indicate multiply ,which plays havoc with my habituated model but trees are green sometimes.
Another way to think about it, is to think of a pipe and stretching that pipe to double its length. Water will have a tougher time getting through the stretched pipe, so you know resistance will increase.
That’s a great analogy for building qualitative intuition. Thanks for the comment!
I have a resistor stretcher, to get custom values.
Why anybody would find it difficult to answer this, I don't understand. The resistance of wire per unit length (at a sufficiently low frequency to avoid the complication of the skin effect) varies inversely with the cross sectional area. If the wire is stretched to double the length, it halves the cross section area, which means the resistance per unit length must be doubled. However, the resistance of the wire also varies linearly with its length, and as the wire is now twice as long, and has twice the resistance per unit length, it means the overall resistance is quadrupled.
Normal caveats apply, such as the cross-sectional area remains constant along the length, the current is low enough that there is no significant heating effect (which increases resistance in metals) and so on.
Students learning about resistance for the first time often struggle with such conceptual questions. Great answers and caveats, though! Spoken like an electrical engineer.
Most of our videos are targeted at high school physics teachers to help them 1) engage their students in productive dialogue and 2) develop pedagogical content knowledge (an understanding of student misconceptions, etc)…
We will be making and uploading more advanced content early in the new year, so feel free to subscribe and keep an eye out for that!