Finding the voltage supply (picture included)

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SUMMARY

The discussion focuses on calculating the voltage supply using the formula V = I x R. The user initially attempted to use the power formula P = V^2 / R1 but encountered issues, as they mistakenly used the resistance value of R1 instead of R2. The correct resistance value for R2 is 9 ohms, which is essential for accurately determining the voltage supply. The book states that the correct voltage supply is 27 volts.

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  • Understanding of Ohm's Law (V = I x R)
  • Familiarity with power calculations (P = V^2 / R)
  • Knowledge of resistance values in a circuit
  • Basic algebra for solving equations
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  • Review Ohm's Law and its applications in electrical circuits
  • Study power dissipation in resistors and how to calculate it
  • Learn about series and parallel resistor configurations
  • Explore practical examples of voltage supply calculations in circuits
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Electronics students, electrical engineers, and hobbyists working on circuit design and analysis will benefit from this discussion.

Josh225
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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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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
 
The value of R2 was 9. Sorry, should have included that.

Oh wow... I see now. Thanks!
 

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