Pomposity, it seems, knows no bounds.

If the shoe fits, wear it.

 

The title and text in the picture posted say it's a voltage divider exercise. When I was in school, if you were told to solve a problem a certain way and you solved it using a different method, 0 credit was awarded for not following directions; even if you arrived at the correct answer.

My goal is to help the TS learn concepts and not just how to throw equations they don't understand at a problem. That's just helping them dig the hole they are already in deeper and deeper instead of helping them climb out. Once they are out of the hole, they will be in a position to solve the problem under the conditions of the problem statement from a standpoint of actually understanding not only why that solution is valid, but in a much better position to be able to apply it properly in less familiar situations. In all likelihood, that's the root of the current inability to solve this problem by treating it as a voltage divider -- it doesn't look exactly like the examples problems they've seen thus far with a voltage source across two resistors. Instead, they are faced with an equation that needs two resistances and the problem has four and no source to use as the V in the formula, so they are stuck, because they don't understand what the voltage divider formula is, where it comes from, what is required to make it applicable, and how to match up the parameters in the problem to the variables in the formula.

 

MOD NOTE: @Papabravo, @dl324: Please, take a step back and try to stop turning this into a personal tiff between the two of you.

 

The formula for a voltage divider is derived from Ohm's Law, which is the fundamental knowledge that is required for solving this problem.

The TS might have assumed that this is a problem pertaining to a voltage divider. However, this can be solved with no knowledge of voltage dividers. It is easily solved by application of Ohm's Law.

Simply stated:

V1 = I x R1
V2 = I x R2
V3 = I x R3
V4 = I x R4

Here we have 4 equations and 5 unknowns.
We need to find a 5th equation which is easily found by visual inspection of the problem given.

Without giving the solution, I leave it up to the TS to state that 5th equation.

 

The TS might have assumed that this is a problem pertaining to a voltage divider.

More likely, though only the TS knows for sure, it wasn't an assumption, but rather an explicit requirement of the problem. Most problems can be solved multiple ways, but in most academic settings, the methods that are allowed on assigned problems are specified since the purpose it to develop and/or assess the student's ability to work with the particular material that the assignment is tied to.

 

@Alex1700 Show us your best attempts to set up the voltage divider equation for your problem. Then we can give guidance where you seem to be struggling. If you don't know where to start, consult your notes or textbook. If you're still struggling, tell us what you understand.

 

View attachment 300875
May i know what is the voltage drop at V3 ?

Title: Understanding Basic Electronics, 1st Ed.
Publisher: The American Radio Relay League
ISBN: 0-87259-398-3