The discussion revolves around calculating the combined resistance in a circuit when a switch is closed. Participants are examining the relationship between current and resistance using Ohm's law, and there is a focus on the implications of combining resistors in different configurations.
The discussion is ongoing, with participants providing insights and questioning each other's reasoning. There is no clear consensus on the correct approach to calculating the combined resistance, and multiple interpretations of the problem are being explored.
Some participants mention the need for clarity on how to combine resistors in the circuit configuration presented, and there are references to potential discrepancies in the provided answer of 4Ω compared to calculated values.
Show your work. Show how you combine various resistors to get the total resistanceEitan Levy said:
I didn't think I should do this. Why is it wrong to just divide the voltage by the total current? This gives 4.2 instead of 4. We didn't study how to really combine the resistors when they are connected like this.phinds said:
You have computed something with the switch open and you are applying it when the switch is closed. That just flat does not work. You HAVE to figure out the combined resistance with the switch closed.Eitan Levy said:
What do you mean? These currents are for when the switch is CLOSED, not open.phinds said:
They how could you possibly have gotten it without combining the resistors?Eitan Levy said:
How do you know that the answer is 4Ω ? Was this a multiple choice question? Or perhaps they want the result rounded to an appropriate number of significant digits?Eitan Levy said:
I thought it doesn't matter how I reached those currents. I did combine the resistors in order to reach those current, and they are correct.phinds said:
Maybe they did but it would be very unusual. This is the answer written in the answers as correct.gneill said:
Eitan Levy said:
So you don't think you should combine the resistors but you did combine the resistors?Eitan Levy said:
This method is correct provided that your current values are correct. If, for correct current values, your result doesn't match the supplied answer for the total resistance with the appropriate number of significant figures for the given data, then that supplied "correct" value is not accurate.Eitan Levy said:
phinds said:
Alright, thanks for the help!gneill said:
