A Question about Parallel Resistances

[bibo_dvd]

Hello Guys !

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

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 !

 

[UltrafastPED]

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).

 

[dlgoff]

Your ohm meter has a battery that supplies a current to your circuit. Here's what's happening (V_B would be you meters battery supply):

http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html

 

[sophiecentaur]

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.)

 

[alphy]

Hello,

Thank you for your question. It is important to understand the concept of parallel resistances in order to answer your question. In parallel circuits, the total resistance is always less than the smallest individual resistance. This is because the current has multiple paths to flow through, so it splits up between the different resistances. This results in a lower overall resistance.

In the first photo (a), the ohmmeter is connected across the 8 ohm and 2 ohm resistors in parallel. The total resistance in this case is calculated as 8 x 2 / (8 + 2) = 1.6 ohms. This is why the ohmmeter reads 1.6 ohms, as it is measuring the total resistance of the circuit.

In the second photo (b), the ohmmeter is connected across the 2 ohm and 10 ohm resistors in parallel. The total resistance in this case is calculated as 2 x 10 / (2 + 10) = 1.67 ohms. Again, the ohmmeter is measuring the total resistance of the circuit, which is 1.67 ohms.

So, to answer your question, the ohmmeter cannot read the individual resistances in these cases because it is measuring the total resistance of the parallel circuit. I hope this helps to clarify your doubts. Let me know if you have any further questions. Thank you.