Equivalent Resistance: To Include or Not to Include r5 and r6?

[sniderman]

Homework Statement

Trying to find equivalent resistance between points a and b.Dont know whether to include resistances r5 and r6.

Thanks

Homework Equations

The Attempt at a Solution

Im not sure what to do with the resistances r5 and r6in the open circuits are they apart of the calculations? i think they are not because nothing should be flowing threw them.
without them i got 1.6 ohms for a equivalent resistance

 

[berkeman]

Homework Statement

Trying to find equivalent resistance between points a and b.Dont know whether to include resistances r5 and r6.

Thanks

Homework Equations

The Attempt at a Solution

Im not sure what to do with the resistances r5 and r6in the open circuits are they apart of the calculations? i think they are not because nothing should be flowing threw them.
without them i got 1.6 ohms for a equivalent resistance

Welcome to the PF.

Imagine connecting a resistance meter (DVM) between points a and b. That will put a voltage across those 2 points, which will cause currents to flow in some of the resistors. If points c and d are floating during this measurement, will there be any currents through R5 and R6?

 

[sniderman]

i want to say that there is no current through those wires, because their not connected to anything making them open circuits?

 

[gneill]

If no current flows through a component then it will not contribute to the resistance.

 

[sniderman]

ok, but is there current flowing in r5 and r6

 

[gneill]

ok, but is there current flowing in r5 and r6

Where would it flow to? You need a CIRCUIT (closed path) for current to flow.