A Question about Parallel Resistances

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Discussion Overview

The discussion revolves around the behavior of an ohmmeter when measuring resistances in parallel circuits. Participants explore why the ohmmeter reads total resistance rather than individual resistances in specific configurations.

Discussion Character

  • Technical explanation, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant questions why the ohmmeter cannot read the individual 8 ohm resistance in a specific configuration.
  • Another participant suggests that to measure the resistance of a component accurately, it often needs to be disconnected from the circuit.
  • A third participant explains that the ohmmeter has an internal battery that supplies current, affecting the readings based on the circuit configuration.
  • It is noted that when multiple paths for current exist, the ohmmeter measures the total current supplied and calculates total resistance, without distinguishing between individual resistors.
  • One participant indicates that to measure each resistor separately, it is necessary to disconnect at least one end of the other resistors.

Areas of Agreement / Disagreement

Participants express varying views on the operation of the ohmmeter and the necessity of disconnecting components for accurate measurements. No consensus is reached on the best approach to measure individual resistances in parallel configurations.

Contextual Notes

Participants do not fully explore the implications of circuit configurations or the specific conditions under which the ohmmeter readings are taken. There is also a lack of detailed discussion on the limitations of the ohmmeter's internal battery and its impact on measurements.

bibo_dvd
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Hello Guys !

My question is : why in these photos the ohmmeter reads the total resistance ??

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I mean why in (a) the ohmmeter can't read the 8 ohms resistance ?

and

Why in (b) the ohmmeter can't read the (2||10 ) resistance ?

Thank you Guys ! :))
 
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If you want the resistance of a component you often need to disconnect it from the circuit.

In this case the connections for the ohmmeter in (a) would give the same reading if you slid the contacts along the wires to a position as shown in (d).
 
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If there are many paths for current to take then it will take them. The meter just measures the amount of current that it supplies from its internal source of volts and does the Sum R = V/I. It can't know which portion of the current is going through which resistor. So you need to measure each resistor separately. This will involve disconnecting one end of the other two. (You needn't disconnect both ends.)
 

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