4 ms·
His technical errors include the “correct” multiple-choice answer being that the time to turn on is “1/c s”. That evaluates to 3.3e-9 s^2/m. It’s not even a tim
by BenFrantzDale 5y ago
His technical errors include the “correct” multiple-choice answer being that the time to turn on is “1/c s”. That evaluates to 3.3e-9 s^2/m. It’s not even a time. Failing basic dimensional analysis is grossly sloppy.
- Lerc 5y agoThe correct units would have tipped his hand and led people to realize the 1m separation of the wires is relevant and thus people would reconsider antenna approaches. That would blunt the gotcha effect. That's not sloppy, it's disingenuous.
- shukantpal 5y agoIt should be obvious that the "c" here was used as a magnitude not with units. Saying that's "failing dimensional analysis" is in itself grossly sloppy - since it totally misses the context.
- SAI_Peregrinus 5y ago1m/cs is the correct value. Not 1/cs. The meters matters, hiding it makes it less obvious that the wire separation is what matters.
- elsjaako 5y agoIf you're going tot quibble about the units, it should be "1m/c". " 1m/c s" gives a result in s².
- deleted 5y ago[deleted]
- BenFrantzDale 5y agoBut dimensioned quantities are meaningless without units. are you saying c has a value of 1.803e+12? Or that it has a value of 1? There’s a big difference between using furlongs per fortnight and speed of light as your units for speed. By saying “1/c s” rather than “1 m/c” he was just plain wrong and certainly in no position to be smug about it.
- shukantpal 5y agoThat’s like being a grammar Nazi even when someone writes something otherwise totally clear. And it’s obvious in this case that the magnitude of c was in metric units. And how do you know if he was even referring to the speed of light by “c”? I could call that a dumb assumption. Because it’s obvious he was using it in a non standard way “magnitude of the speed of light in m/s”.