Timeline for Ambiguity in voltage measurement
Current License: CC BY-SA 4.0
17 events
| when toggle format | what | by | license | comment | |
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| Apr 5, 2019 at 15:13 | comment | added | Peter Bennett | But you didn't SAY where the black meter lead was connected, so how were we to know what your reference point was? The point is that you must specify what point you are using as a reference/zero volts. | |
| Apr 5, 2019 at 10:13 | comment | added | penguin99 | @Peter Bennet, the black lead remains where it is. In the middle | |
| Apr 5, 2019 at 0:15 | comment | added | Peter Bennett | You say: " I first connect the red lead at the top to measure 12V. I then connect the red lead to the bottom to measure -12V,", but don't mention where you connected the black meter lead. Where you connected the black lead is important! You always measure voltage between two points. Conventionally, we call some point in a circuit "Zero Volts" and mark that point with a "Ground" symbol. We then put the black lead of the meter on that Zero volts/Ground point when measuring voltages elsewhere in the circuit. | |
| Apr 4, 2019 at 18:51 | vote | accept | penguin99 | ||
| Apr 4, 2019 at 18:51 | |||||
| Apr 4, 2019 at 18:45 | answer | added | Transistor | timeline score: 1 | |
| Apr 4, 2019 at 18:22 | comment | added | G36 | electronics.stackexchange.com/questions/392010/… | |
| Apr 4, 2019 at 18:18 | answer | added | TimWescott | timeline score: 1 | |
| Apr 4, 2019 at 18:14 | comment | added | The Photon | For comparison, if Los Angeles is at +93 m relative to sea level and Death Valley is -86 m relative to sea level, that means LA is 179 m above Death Valley, not 9 m above Death Valley. | |
| Apr 4, 2019 at 18:09 | comment | added | The Photon | No, you need to subtract. The voltage between B and C (\$V_{BC}\$) is \$V_{BC} = V_B-V_C = (V_B-V_A)-(V_C-V_A)\$. | |
| Apr 4, 2019 at 18:07 | answer | added | The Photon | timeline score: 1 | |
| Apr 4, 2019 at 18:04 | comment | added | penguin99 | @the photon, wouldn't it be a simple addition of +12V + (-12V) to give zero voltage? | |
| Apr 4, 2019 at 18:03 | history | edited | penguin99 | CC BY-SA 4.0 |
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| Apr 4, 2019 at 18:03 | comment | added | The Photon | Why do you say that there is a "net voltage" of 0? You measured +12 V from point a to point b. and -12 V from point a to point c. That implies voltage from point c to point b will be 24 V, not 0 V. | |
| Apr 4, 2019 at 18:02 | comment | added | Voltage Spike♦ | There is ambiguity in your question. I would redo your question with a schematic (use the tool) and label points, then reference them in your question. | |
| Apr 4, 2019 at 18:01 | comment | added | penguin99 | So what I'm doing is, I first connect the red lead at the top to measure 12V. O then connect the red lead to the bottom to measure -12V, getting a net voltage of 0v. | |
| Apr 4, 2019 at 17:59 | comment | added | Wouter van Ooijen | 1) Your diagrams don'tt show the + and - labels for the batteries. add them. 2) In the first diagram I don't get waht the dashed lines mean. You can't meaningfully connect the V meter to both the -12V and the +12V sides. | |
| Apr 4, 2019 at 17:53 | history | asked | penguin99 | CC BY-SA 4.0 |