# Finding the voltage in a resistance

• znaya
In summary, the question asks for the voltage in R3 in a circuit with a 2A current source and several resistors. Using Ohm's law and simplifying the circuit to find the equivalent resistance, the voltage in R3 is calculated to be 25V. This aligns with the answer options provided, suggesting a possible mistake by the professor in the options.
znaya

## Homework Statement

Given the circuit in the image (with a current source of 2A and several resistors), what's the voltage in R3?

http://postimg.org/image/yl6czh9u7/

1.1V
0.77V
50V
0.55V

Ohm's law.
V=RI

## The Attempt at a Solution

I tried to simplify the circuit. The circuit equivalent resistor I found was
(((((R6 || R7) + R5) || R8) + R4) || R3) + R1 + R2
From my calculation the equivalent resistor is 32,5Ω
And the voltage of the circuit is 65V
If the voltage in R1 is 10V (2A x 5Ω) and in R2 is 30V (2A x 15Ω) in R3 it should be something like 25V... but that is none of the options!
Thanks for any help.

Last edited:
I agree with your analysis and I got the same result.

Here is a nice shortcut once you have the expression for the equivalent resistor: you have R3 and an equivalent resistance of 25 Ohm in parallel, so the 2 A will be split in two equal parts - R3 will get 1 A and therefore a voltage of 25 V.

1 person
I tried to solve this problem hundreds of times using different approaches and the result was always 25Ω.
Maybe the professor mistook when he chose the answer options...

## 1. What is voltage?

Voltage is the measure of electric potential difference between two points in an electrical circuit. It is measured in volts (V).

## 2. What is resistance?

Resistance is the measure of how much a material or component impedes the flow of electric current. It is measured in ohms (Ω).

## 3. How do I calculate voltage in a resistance?

Voltage can be calculated by multiplying the current (I) flowing through a resistor by the resistance (R) of the resistor, using the formula V = IR.

## 4. Can voltage be measured in a circuit with multiple resistors?

Yes, voltage can be measured in a circuit with multiple resistors. In this case, the total voltage is equal to the sum of the individual voltages across each resistor.

## 5. What factors affect the voltage in a resistance?

The voltage in a resistance can be affected by the amount of current flowing through the resistor, the resistance value of the resistor, and the circuit's power source. Other factors such as temperature and the material of the resistor can also impact the voltage.

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