# Voltage devider

Discussion in 'Homework Help' started by fury, Sep 22, 2011.

1. ### fury Thread Starter New Member

Sep 22, 2011
4
0
Hi, folks. ... this my first post.
Im new in electrical circuits, so i have dummy question about voltage divider. I really can't managet to do this example from socratic project:

http://www.ibiblio.org/kuphaldt/socratic/output/e_divide.pdf problem 15.

If the both resistors are in series - no problem i will use $Vout = Vin \frac{mR1}{R1+R2}$ But if they are in parallel i try with formula $Vout = Vin\frac{mR1R2}{R1+R2}$ and nothing - rong answer. So i need help for that!

Thanks !

2. ### mrmount Active Member

Dec 5, 2007
59
7
If the resistors are in parallel they will have the same voltage across them.

3. ### Adjuster Late Member

Dec 26, 2010
2,147
302
Question 15 - the 5kΩ potentiometer.

For the 0% and 100% settings the answer should be obvious, but for each of the other settings redraw the pot as a two-resistor divider.

The resistance to ground will be the given percentage of the total, and the resistance to supply will be the total minus the resistance to ground.

Now calculate the effective value of the resistance to ground by working out the parallel combination with the 1kΩ.

Finally work out the modified division ratio, multiply by the input voltage, and you will have the answer.

4. ### fury Thread Starter New Member

Sep 22, 2011
4
0
Thanks Adjuster ... its works !