Finding the voltage supply (picture included)

In summary, to calculate the value of the voltage supply, use the formula V= I x R. If given the value of R2, substitute it into the equation to find the voltage supply. If only given the resistance and power for R2, use the formula P= V^2 / R to find the voltage supply. Make sure to use the correct value for R2 in the equation. In this case, the value of R2 was 9 and the voltage supply was calculated to be 38.18.
  • #1
Josh225
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Member advised to use the homework template for posts in the homework sections of PF.
I have been having trouble calculating the value of the voltage supply. From what I have learned, to calculate the value, it is V= I x R. I have already calculated the value of R2 as the problem asks, but how do I find the voltage supply if I only know the resistane and the power being distributed to R2?

I tried using P= V^2 / R1 to try to find V, but it didn't work out for me:

V^2= 81 (18)= 1458
V= √1458
V= 38.18

The book says the answer is 27
 

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  • #2
You are given the power dissipated in R2.

18 ohms is the value of R1, not R2. You need to use the value for R2 in your equation...

What did you get for R2
 
  • #3
The value of R2 was 9. Sorry, should have included that.

Oh wow... I see now. Thanks!
 

1. How do I determine the voltage supply from a picture?

To determine the voltage supply from a picture, you will need to first identify the components in the circuit and their corresponding values. From there, you can use Ohm's Law (V = IR) to calculate the voltage supply by measuring the current and resistance in the circuit.

2. Can I use a multimeter to find the voltage supply?

Yes, a multimeter is a commonly used tool for finding the voltage supply in a circuit. You can use the multimeter to measure the voltage across a component in the circuit and use Ohm's Law to calculate the voltage supply. Make sure to set the multimeter to the appropriate voltage range.

3. Is there another way to find the voltage supply besides using Ohm's Law?

Yes, you can also use Kirchhoff's Voltage Law (KVL) to determine the voltage supply. KVL states that the sum of all voltage drops in a closed loop circuit must equal the sum of all voltage sources. By measuring the voltage drops across each component and solving for the voltage supply, you can find the voltage supply without using Ohm's Law.

4. What if there are multiple voltage sources in the circuit?

If there are multiple voltage sources in the circuit, you can use KVL to determine the total voltage supply by considering all the voltage sources in the loop. Make sure to take into account the polarity of each voltage source when applying KVL.

5. Can I use a circuit simulator to find the voltage supply?

Yes, circuit simulators can also be used to find the voltage supply. You can input the circuit components and their values into the simulator and it will calculate the voltage supply for you. However, it is still important to understand the principles behind finding the voltage supply in case of any errors or discrepancies in the simulation.

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