Voltage Divider Rule
The Voltage Divider Rule is used to calculate the voltage drop across resistors connected in series. It helps determine how the input voltage is divided among the resistors.
Formula:
If two resistors are in series across a voltage source:
Vx = (Rx / (R₁ + R₂)) × Vtotal
Example 1: Two Resistors
A 12 V source is connected across two resistors in series: R₁ = 4 Ω and R₂ = 8 Ω. What is the voltage across R₂?
Formula: VR2 = (R₂ / (R₁ + R₂)) × V
Calculation: V = (8 / (4 + 8)) × 12 = (8 / 12) × 12 = 8 V
Answer: The voltage across R₂ is 8 volts.
Example 2: Three Resistors
A 15 V source is connected across three resistors in series: R₁ = 2 Ω, R₂ = 3 Ω, R₃ = 5 Ω. What is the voltage across R₂?
Total resistance: Rtotal = 2 + 3 + 5 = 10 Ω
VR2: V = (3 / 10) × 15 = 4.5 V
Answer: The voltage across R₂ is 4.5 volts.