function [x]=wheatstone(r3,r4); %wheatstone(r3,r4) takes input values for resistors 3 and 4 and plots the %current vs. r2 assuming that V=6 volts, and r1=1 ohm and rA=.001 ohms. r1=1; rA=0.001; V=6; r2=(0:.05:100); %expression for current vs. resistance of r2 y=([V.*(r2.*r3-r1*r4)]./[r2.*(rA*r1+rA*r3+r1*r3+r4*r1+r4*r3)+rA*r3*r4+rA*r1*r4+r1*r3*r4]); %expression for change in current vs change in resistance der=((([V*((1+10^-12)*r3-r1*r4)]/[(1+10^-12)*(rA*r1+rA*r3+r1*r3+r4*r1+r4*r3)+rA*r3*r4+rA*r1*r4+r1*r3*r4])-([V*((1-10^-12)*r3-r1*r4)]/[(1*10^-12)*(rA*r1+rA*r3+r1*r3+r4*r1+r4*r3)+rA*r3*r4+rA*r1*r4+r1*r3*r4]))/(2*10^-12)) figure;cla; plot(r2,y); axis([0 20 -1/r3 1/r3]); xlabel('Resistance of r2 (ohms)'); ylabel('Current through ammeter (A)');