Electronic – High resistance, no current. What’s the point of a potential then

currentresistorsvoltage

I am referring to this example:

enter image description here

  1. Why does it matter that the IC has a high resistance? What does this do for/to the IC?

  2. If there is a potential but no current, what is the point of using the IC when in the end no current would run through? Would the device even work?

Best Answer

We can apply voltage divider rule only when same current is running through these resistors. This means, if the IC is supposed to draw current, sum of two currents: one towards the IC and another towards the R2 passes through the resistor R1. So there is difference in the currents flowing throught R1 and R2. Look at the schematic I have added. I have just tried to show how the current flows when there is low resistance in parallel circuit.

So by considering high resistance of IC, we can neglect the current flowing through the IC and apply the voltage divider rule.

schematic

simulate this circuit – Schematic created using CircuitLab

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