Can anyone (or everyone) help me figure out why my values for % Difference Volta

Question

Can anyone (or everyone) help me figure out why my values for % Difference Voltage Drops are so high? I don't understand what is wrong.

This is for resistors in series. More information is provided below the table.

Terminal Voltage Vt = 1.55V

Total Theoretical Current = Vtotal / Req = 0.0107A = 10.7mA

measured current I'i (mA) measured voltage drop V'i (V) Theoretical Voltage Drop Vi (V) % Difference Voltage drop R1 9.80 0.98 0.11 159.6% R2 9.79 0.33 0.36 8.7% R3 9.81 0.097 1.07 166.7% Total Voltage Drop ****************** 1.407 1.54 9.03%

Explanation / Answer

I think I can give you some suggestions.

Your calculations are well in general

* You found the equivalent resistance and with this meet the circuit current is Constant for being a serial circuit.

1 posibilility

Let me do the math considering the internal resistance of the source

Req = R1 +R2+R3 + Ri

Req = 144.5 + Ri

V = I Req

I will use the average of current measurements

Ipro= (9.80 +9.79 +9.81)/3

Ipro= 9.80 mA

Ipro= 0.00980 A

With the terminal voltage and the measured current calculate the internal resistance of the source

V = IproReq

Req= V /Ipro

Req = 1.55/0.00980

Req = 158.16

144.5 +Ri = 158.16

Ri = 158.16 - 144.5

Ri= 13.66

2 Posibilidad

There is a hidden voltage drop at the source, to calculate subtract the terminal voltage and total voltage

Vi = 1.55 – 1.407

Vi = 0.143 V

We calculate the current with this lower voltage

V = I Req

I =V/ Req

I = 1.407 / 144.5

I= 0.009737 A

I= 9.737 mA

We can see that the current calculated with the two possibilities are very similar, so we will calculate the voltages with this new current

V1 = I R1

V1 = 0.009737 10.7

V1 = 0.104 V

% Dif = (V1 -Vm)/Vm 100

% dif = (0.104 – 0.98)/0.98 100

% Dif = 89%

V2 = 0.009737 33.8

V2 = 0.329 V

% Dif = (V2 -Vm)/Vm 100

% dif = (0.329 – 0.33)/0.33 100

% Dif = 0.27%

V3= i R3

V3 = 0.009737 100

V3 = 0.9737 V

% Dif = (V1 -Vm)/Vm 100

% dif = (0.9737 – 0.097)/0.097 100

% Dif = 900%

We see that the difference between the values except for R2 is very high

3 Possibility

There is an error on the labels of resistance

Values that have been

R1 = 100

R2 = 33.8

R3 = 10.7

Again, we should assume an internal source resistance to give the current

Ri = 13.66

with these values we will calculate the voltages

V1 = 0.009737 100

V1 = 0.9737 V

%Dif = 0.6%

V2 = 0.009737 * 33.8

V2 = 0.329 V

%Dif = 0,3%

V3 = 0.009737 * 10.7

V3 = 0,1042

%Dif = 7.4%

These errors are small,

Result:

After this analysis I think there are two things in the circuit:

1) the existence of an internal source resistance of the order of Ri = 13.66

2) An error in the label of resistance, R1 and R3 are exchanged

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