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+//CHAPTER 8- DIRECT CURRENT MACHINES
+//Example 20
+
+disp("CHAPTER 8");
+disp("EXAMPLE 20");
+
+//VARIABLE INITIALIZATION
+v_t=250;                    //in Volts
+I_a1=20;                    //in Amperes
+N1=1000;                    //in rpm
+r_a=0.5;                    //in Ohms
+drop=1;                     //brush contact drop in Volts
+ratio=1.5;                  //N2:N1=1.5
+phi1=1;                     //it is an assumption
+
+//SOLUTION
+E_1=v_t-(I_a1*r_a)-(2*drop);
+//solving the quadratic equation directly,
+a=1;
+b=-496;
+c=14280;
+D=b^2-(4*a*c);
+x1=(-b+sqrt(D))/(2*a);
+x2=(-b-sqrt(D))/(2*a); 
+if(x1<40)
+I_a2=x1;
+else if(x2<40)
+I_a2=x2;
+end;
+phi2=(I_a1/I_a2)*phi1;
+phi=(1-phi2)*100;
+disp(sprintf("The flux to be reduced is %f %% of the main flux",phi));
+
+//END