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| Veritasium "How Electricity Actually Works" |
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| timenutgoblin:
--- Quote from: electrodacus on May 03, 2022, 12:40:07 am ---If those two capacitors are identical (same capacity) the voltage after switch is closed will be 0.707 * Vi --- End quote --- That's not how physics works. You're implying that energy can be created out of nothing to buffer an energy deficit. Using the water analogy, if you have two buckets of the same capacity to represent the two capacitors, then one bucket is filled and the other is empty. This is the initial condition. If you pour 70.7% of the water from the filled bucket into the empty bucket, then there will be 29.3% of the water remaing in the initially-filled bucket. How can there also be 70.7% water remaining in the initially-filled bucket when only 29.3% of the water remains in that bucket? That is absurd and contradictory. That's the definition of a paradox. |
| electrodacus:
--- Quote from: timenutgoblin on May 03, 2022, 01:05:05 am --- That's not how physics works. You're implying that energy can be created out of nothing to buffer an energy deficit. Using the water analogy, if you have two buckets of the same capacity to represent the two capacitors, then one bucket is filled and the other is empty. This is the initial condition. If you pour 70.7% of the water from the filled bucket into the empty bucket, then there will be 29.3% of the water remaing in the initially-filled bucket. How can there also be 70.7% water remaining in the initially-filled bucket when only 29.3% of the water remains in that bucket? That is absurd and contradictory. That's the definition of a paradox. --- End quote --- What extra energy are you seeing ? There is no extra energy. Half of the energy stored in the charged capacitor is transferred to the identical capacity discharged capacitor and that will result in 0.707 * Vi. Voltage is not energy. |
| SiliconWizard:
--- Quote from: electrodacus on May 02, 2022, 10:47:46 pm --- --- Quote from: SiliconWizard on May 02, 2022, 07:31:16 pm ---Well, as I understand it, a medium is needed to hold charges, and if there are no charges, there's no field? The question then is more about fields making charges move rather than charges moving creating fields. Or something. --- End quote --- In this example (Derek's setup) the charges are needed to create the field as the only electric field is inside the battery There is no moving object in this experiment. --- End quote --- I'm not sure you got what I meant, nor that I got what you meant. And nobody talked about moving objects here. |
| electrodacus:
--- Quote from: SiliconWizard on May 03, 2022, 01:29:34 am ---I'm not sure you got what I meant, nor that I got what you meant. And nobody talked about moving objects here. --- End quote --- Maybe you understand magnetic field better. If you add a permanent magnet somewhere in Derek's setup. Will that magnetic field do any work if neither the magnet nor the wires are moving relative to each other? Similarly in a setup like the one Derek made where none of the components move relative to each other from where will you have an electric field. When electrons will start to move you will get both an electric field and also a magnetic field. |
| hamster_nz:
--- Quote from: electrodacus on May 03, 2022, 01:22:57 am --- --- Quote from: timenutgoblin on May 03, 2022, 01:05:05 am --- That's not how physics works. You're implying that energy can be created out of nothing to buffer an energy deficit. Using the water analogy, if you have two buckets of the same capacity to represent the two capacitors, then one bucket is filled and the other is empty. This is the initial condition. If you pour 70.7% of the water from the filled bucket into the empty bucket, then there will be 29.3% of the water remaing in the initially-filled bucket. How can there also be 70.7% water remaining in the initially-filled bucket when only 29.3% of the water remains in that bucket? That is absurd and contradictory. That's the definition of a paradox. --- End quote --- What extra energy are you seeing ? There is no extra energy. Half of the energy stored in the charged capacitor is transferred to the identical capacity discharged capacitor and that will result in 0.707 * Vi. Voltage is not energy. --- End quote --- Really? This? Again? Charge is the conserved quantity. In a capacitor the voltage is proportional to the charge (due to the very definition of Capacitance) so in this case voltage is conserved too. Electrical energy does not have to be conserved in an electric circuit - it is often converted to some other form of non-electrical energy (heat. light, motion, radio waves and sometimes smoke). You will never, never, never, never, never, never, never, ever get a stable state with 0.707 * Vi. If you don't believe me take it up with this random internet guy from Princeton: https://physics.princeton.edu/~mcdonald/examples/twocaps.pdf "If there were no damping (dissipative) mechanism, the circuit would then oscillate forever" "[if there is a damping (dissipative) mechanism] eventually a static charge distribution results, with charge Qi/2 and voltage Vi/2, on each capacitor." |
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