Solving a Simple Circuit Analysis Homework Problem: Finding Voltage Drop

[jumbogala]

Homework Statement

I have a box which has two resistors in it, R1 and R2. The box has three terminals: a red, black, and white terminal.

A voltage source of 10 V is connected across the red and black terminals.

If I connect a voltmeter across the red and white terminals, what is the expected voltage reading given that R1 = 1 ohm and R2 = 1 ohm?

Homework Equations

V = IR

The Attempt at a Solution

I thought R1 and R2 are in series, so their equivalent resistance is 2 ohms. Then I used V=IR to find the current through the box... 10 V/ 2 ohms = 5 A. Then I multiplied 5 A by 1 ohm (the value of R1) to find the voltage drop to be 5 V across R1. I'm not sure if that's right because are R1 and R2 really in series? And is the measured voltage going to be the combined drop through R1 and R2, or just through R1?

Help!

 

[anathema]

Hi there! It seems like you are on the right track with your thinking. R1 and R2 are indeed in series, which means that the current flowing through them will be the same. In this case, the current is 5 A.

When using V=IR, you are calculating the voltage drop across a single resistor. So in this case, the voltage drop across R1 will be 5 V and the voltage drop across R2 will also be 5 V.

When you connect a voltmeter across the red and white terminals, you are essentially measuring the voltage drop across R1 and R2 together. So the expected voltage reading will be 10 V, which is the same as the voltage of the source.

I hope this helps clarify things for you! Let me know if you have any other questions.

 

[tomcue]

Your approach is correct. R1 and R2 are indeed in series, as they share a common current path. The measured voltage across the red and white terminals will be the combined voltage drop across both resistors. In this case, it will be 5 V, as you correctly calculated. Keep in mind that in a series circuit, the current is constant throughout, but the voltage is divided among the resistors based on their individual values. So in this case, R1 and R2 will each have a voltage drop of 5 V, since they have equal resistance values.