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Getting incorrect output for Parallel Circuit resistance

BenW (7)
Hi all,

I'm having trouble with—I believe—getting incorrect output from the second part of the bool statement here. The code's running, and I believe the Series Circuit statment is correct, but not the second part..

Any help would be much appreciated.

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#include <iostream>
#include <cmath>
#include <iomanip>

using namespace std;

int main() {
    
    char C;
    char S;
    char P;
    double R;
    double R1;
    double R2;
    double R3;
    double I;
    double V=12;
    double Rr;
    
    cout << "Please enter S for Series Circuit or P for Parallel Circuit" << endl;
    cin >> C;
    
    
    if (C == 'S') 	{
        cout << "This program will calculate the total resistance (R) given three resistor values (R1,R2,R3) in ohms" << endl;
        cout << "Please enter the first resistor value (R1) in ohms:" << endl;
        cin >> R1;
        cout << "Please enter the second resistor value (R2) in ohms:" << endl;
        cin >> R2;
        cout << "Please enter the third resistor value (R3) in ohms:" << endl;
        cin >> R3;
        R = R1+R2+R3;
        I = V/R;
        cout << "R = " << R << endl;
        cout << "I = " << I << endl;
    }
    
    else if (C == 'P') 	{
        cout << "This program will calculate the total resistance (R) given three resistor values (R1,R2,R3) in ohms" << endl;
        cout << "Please enter the first resistor value (R1) in ohms:" << endl;
        cin >> R1;
        cout << "Please enter the second resistor value (R2) in ohms:" << endl;
        cin >> R2;
        cout << "Please enter the third resistor value (R3) in ohms:" << endl;
        cin >> R3;
        R = (1/R1) + (1/R2) + (1/R3);
        Rr = (1/R);
        I = V/R;
        cout << "R = " << R << endl;
        cout << "I = " << I << endl;
    }
}
AbstractionAnon (6954)
In lines 46 and 47, you're reversed R and Rr.

Parallel resistance formula is: 1/Rtotal = 1/r1 + 1/r2 + 1/r3.
i.e. The result of line 46 is a reciprocal. 

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47
 
        Rr = (1/R1) + (1/R2) + (1/R3);
        R = (1/Rr);


Last edited on
BenW (7)
Lol oh man.

Yeah that fixed it. Thanks so much!
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