Which side of a resistor is positive/negative?

[miyayeah]

Homework Statement

In the attached file, how do I decide which side of the resistor is positive/negative?

Homework Equations

N/A

The Attempt at a Solution

The current would go through the 6V battery starting from the positive end of the 9V battery to the negative end of the 9V battery; so my guess is that the right side of 4Ω resistor is positive, and the other side is negative.

 

[berkeman]

Homework Statement

In the attached file, how do I decide which side of the resistor is positive/negative?

Homework Equations

N/A

The Attempt at a Solution

The current would go through the 6V battery starting from the positive end of the 9V battery to the negative end of the 9V battery; so my guess is that the right side of 4Ω resistor is positive, and the other side is negative.

I agree with your answer.

In the general case where it is not so easy, use KCL equations to solve for the voltages and currents in a circuit. Can you post those to double-check your answer?