Voltage in series + parallel resistor circuit

S

Sawyer

New Member

• Feb 24, 2010

• #1

Ok so this might seem like an easy question but for some reason I just can't figure it out... I know it is probably something really simple but of course I can be a complete idiot sometimes and not see it

**broken link removed**

So lets say S1 is closed, and each of the resistors are 100k Ohms. You measure 3.6 V across resistor R1, 1.2 V across resistor R2, 1.2 V across resistor R3, and 2.4 V across resistor R4. What is the battery voltage in the circuit?

btw this is a question in one of the tests for my online schooling course, but when I mailed the school for help on how to figure it out they literally said look on the internet! lol

 

Hero999

Banned

• Feb 24, 2010

• #2

I don't blame them.

The total voltage across some resistors connected in series is equal to the sum of the voltages across each resistor in series.

For example, the voltage across R2 is 1.2V and the voltage across R3 is 1.2V, therefore the voltage across both R2 and R3 is 2.4V which is also equal to the voltage across R2.

Message to anyone thinking about posting the answer.

PLEASE DO NOT POST THE ANSWER. Let him figure it out for himself because it will help him more.

 

S

Sawyer

New Member

• Feb 24, 2010

• #3

Yeah but 8.4 V isn't one of the available answers.

 

Hero999

Banned

• Feb 24, 2010

• #4

That's because it's wrong.

I suggest you try again.

 

Last edited: Feb 24, 2010

S

Sawyer

New Member

• Feb 24, 2010

• #5

I guess it's true what they say about the british :/

Thanks anyway

 

Hero999

Banned

• Feb 24, 2010

• #6

What's that supposed to mean?

How did you arrive at 8.4V?

 

Last edited: Feb 24, 2010

S

Sawyer

New Member

• Feb 24, 2010

• #7

By adding all the voltages... but then I realized I don't add the voltages in the parallel portion of the circuit to each other... I figured it was something really simple, just completely went by me for some reason

 

Hero999

Banned

• Feb 24, 2010

• #8

The mistake I made in a previous post probably didn't help, here's the correction:

Hero999 said:

For example, the voltage across R2 is 1.2V and the voltage across R3 is 1.2V, therefore the voltage across both R2 and R3 is 2.4V which is also equal to the voltage across R4.

Click to expand...

I take it you got the right answer in the end?

Often it's simple and the circuit is drawn in a complicated way to make you think.

 

S

Sawyer

New Member

• Feb 24, 2010

• #9

6V is what I am assuming it is, R1 + the 2.4V

thanks

 

Last edited: Feb 24, 2010

Hero999

Banned

• Feb 24, 2010

• #10

That's it.