Step 3: What is a Voltage Divider?
One of the best places to learn about Electronic is Wisconsin Online dividers are explained on that page (lower right), or you can visit the Voltage Wikipedia Page.
In short, if you have two resistors in series, the voltage drop across each resistor is in proportion to the size of the resistor. If you have Voltage V across a circuit of R(1) + R(2), then V = V(1) + V(2). So if V=3V and V(2) = 2V, you know that the V(1) = 1V.
Now the basis of Ohm's Law is that the current (I) is V/R. In a series circuit, the current is the same throughout, so the current through A and B is the same for the whole circuit. Therefore I = V1/R1 = V2/R2.
We know V2 = V - V1, Plugging in, we see V1/R1 = (V-V1)/R2. Solving we get R2 = R1*(V-V1)/V1
So if know if we know V(1), V, and R(2), we can solve for R2.
If we have R2, we know the value of the Thermistor!
In short, if you have two resistors in series, the voltage drop across each resistor is in proportion to the size of the resistor. If you have Voltage V across a circuit of R(1) + R(2), then V = V(1) + V(2). So if V=3V and V(2) = 2V, you know that the V(1) = 1V.
Now the basis of Ohm's Law is that the current (I) is V/R. In a series circuit, the current is the same throughout, so the current through A and B is the same for the whole circuit. Therefore I = V1/R1 = V2/R2.
We know V2 = V - V1, Plugging in, we see V1/R1 = (V-V1)/R2. Solving we get R2 = R1*(V-V1)/V1
So if know if we know V(1), V, and R(2), we can solve for R2.
If we have R2, we know the value of the Thermistor!
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