Kathy Loves Physics – Why the U.S. uses 120 volts and not 220 volts
An evening pause: Here’s a bit of technology history that still affects us daily.
Hat tip Tom Biggar.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit.
The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
An evening pause: Here’s a bit of technology history that still affects us daily.
Hat tip Tom Biggar.
On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
The print edition can be purchased at Amazon. from any other book seller, or direct from my ebook publisher, ebookit. The ebook is available everywhere for $5.99 (before discount) at amazon, or direct from my ebook publisher, ebookit. If you buy it from ebookit you don't support the big tech companies and the author gets a bigger cut much sooner.
The audiobook is also available at all these vendors, and is also free with a 30-day trial membership to Audible.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs."--San Antonio Express-News
She has the history correct. I know she is explaining to a general audience about current, voltage, frequency, and 3-phase transmission. One nitpick, on her equation for the line voltage of a 3-phase Wye, it is 1.73 not 1.72. ;)
Another small nit – she starts off explaining about Edison and DC, but then starts talking about transformers, but didn’t mention that they only work on AC.
On Mars, we might start all over again, maybe with superconducting DC that can send information for less birdnesting.
When living in the UK. 220V. Electric blankets: nope.
I wonder about the 60Hz thing: If it were double that, your transformers could get away with being smaller/lighter. I think Navy ships use different voltages/frequencies for losses and efficiency. (They have (450, 120) V lines at (60, 400) Hz). The 400 Hz banks are for powering various systems related to the weapons systems.
She is an amazing teacher
MadRocketSci,
The old standard is 4180v 60Hz for a ship’s main electrical bus, and the new Ford Class Supercarriers are using 14kv. I know that since I had to design a substation to provide ship to shore power to switch between the two.
Yes the Navy uses 400Hz for most large motors and generators on a vessel. You can have smaller transformers with 400Hz compared to 60Hz, the less weight the better on a vessel. When you have a higher frequency, the size of the iron core and wiring of the transformers decreases.
Interesting topic but hard to watch.
I’m guessing she is/was a teacher/lecturer used to speaking at the front of a large classroom/lecture hall.
In such a setting the vocal projection and hand movements work.
She’s not the only YouTuber to forget that typical YouTube camera distances are akin to speaking to someone a few feet away.
Just talk, and keep your limbs under control. And avoid the facial close-ups, we aren’t your dentist! (at least she doesn’t do that)
And when doing a video you can leave the photo or chart on screen and continue to talk. There are excellent YouTube vids where the speaker is not seen at all (Drachinifel’s naval history vids come to mind). That way there is more time for the audience to view those charts and photos
Rant complete!