CHAPTER 14 ■ VARIABLE RESISTORS
- Determine the amount of voltage being used in the path.
V at beginning - V at the end = total V used in the path
This example: 9 V - 0 V = 9 V- Multiply the resistor’s share by the voltage used in the path to determine how
much voltage is used in that resistor.
R1's share × total V of path = V of R1
This example: 0.044 × 9 V = 0.4 VLet’s check the value for R2:R2 W / total W = R2's share
This example: 10,000 W / 10,670 W = 0.937
R2's share × total V of path = V of R2
This example: 0.937 × 9 V = 8.43 V
What’s the deal with that? R2 has the largest resistance, so most of the voltage (pressure) was used up
getting through it. Thus far, R1 and R2 have used up 8.83 V out of 9 V.
R4 W / total W = R4's share
This example: 100 W / 10,670 W = 0.00937
R4's share × total V of path = V of R4
This example: 0.00937 × 9 V = 0.08 V
And R3:R3 W / total W = R3's share
This example: 100 W / 10,670 W = 0.00937
R3's share × total V of path = V of R3
This example: 0.00937 × 9 V = 0.08 V
Evaluating Test Point 1
Now that all of the voltages used along that path have been calculated, it is possible to determine the voltage
at test point 1 (TP1). The battery starts out at 9 V. R1 and R2 use 8.83 V combined. So, around 0.17 V must be
remaining by the time the electricity reaches TP1 (see Figure 14-16).