Voltage divider (circuit analysis)

In summary, the conversation discusses using a voltage divider to solve for V1 in a circuit involving a 10k ohm resistor. The approach taken is to use the loop rule to find the voltage across the 10k device, which is then used to calculate V1. There is some confusion about the equation used to find the voltage across the 10k device, but ultimately the solution is found to be V1 = -20V. There is also a mention of a third picture showing that V1 is the voltage across the 10 ohm resistor.
  • #1
Miike012
1,009
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How am I suppose to use voltage divider to solve for V1?

The first pic is the original pic
The second pic is me solving for V1,Vx, and V2

The third pic is and equivalent circuit of the first pic... I did this to reason that V1 is the voltage across the 10k ohm resistor.

Therefore using voltage divider...
V1 = (Vx - V1)(10/15) = -30(10/15) = -20V.

Is that the correct approach or is there an easier way?
 

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  • #2
Presuming that the polarity shown on the 10k device is the polarity that appears across the diamond,
loop rule is 25V - V_10k - ½V_10k + ¼V_10k = 0 , so that V_10k = 20V = -Vx. (otherwise Vx=14.28V)
(but why isn't their V1 = 25V - V_10k = 25V - 20V = 5V?)
 
  • #3
lightgrav said:
Presuming that the polarity shown on the 10k device is the polarity that appears across the diamond,
loop rule is 25V - V_10k - ½V_10k + ¼V_10k = 0 , so that V_10k = 20V = -Vx. (otherwise Vx=14.28V)
(but why isn't their V1 = 25V - V_10k = 25V - 20V = 5V?)

im confused as to how you came up with the equation 25V - V_10k - ½V_10k + ¼V_10k = 0 .

shouldnt it be...
Eq 1.
25 - Vx/4 + V5 + V10 = 0 ?
and
V10 = Vx.


Next...

V5 = I(5kohm) and I = Vx/(10k ohm).

Now from Eq 1.

25 - Vx/4 + Vx/2 + Vx = 25 + 5/4Vx = 0

and Vx = -25*4/5 = -20



(but why isn't their V1 = 25V - V_10k = 25V - 20V = 5V?)...

I added the third picture in my paint document that shows that V1 is the voltage across the 10 ohm resis.
 
Last edited:

1. What is a voltage divider?

A voltage divider is an electronic circuit that divides a voltage into smaller parts. It is usually composed of two or more resistors connected in series.

2. How does a voltage divider work?

A voltage divider works by using the principle of Ohm's law, which states that the voltage across a resistor is proportional to the current flowing through it. The resistors in a voltage divider divide the input voltage into smaller parts based on their respective resistance values.

3. What is the formula for calculating the output voltage in a voltage divider?

The formula for calculating the output voltage in a voltage divider is Vout = Vin x (R2 / (R1 + R2)), where Vin is the input voltage, R1 and R2 are the resistances of the two resistors in the divider, and Vout is the output voltage.

4. What is the purpose of a voltage divider?

The purpose of a voltage divider is to reduce the voltage of a circuit to a desired level. This is useful in many applications, such as powering electronic devices with different voltage requirements, or measuring high voltages with a lower range voltmeter.

5. What are some practical uses of a voltage divider?

A voltage divider has many practical uses, including adjusting the brightness of an LED, controlling the speed of a motor, and creating reference voltages for analog-to-digital converters. It is also commonly used in power supplies, audio equipment, and sensor circuits.

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