What Is a Current Divider?
A current divider is a principle used in circuit analysis to determine how electrical current splits among parallel branches. When multiple components are connected in parallel, the total current divides inversely proportional to the resistance (or impedance) of each branch.
Why Current Dividers Matter
- Analyzing parallel resistor networks
- Designing analog and power circuits
- Estimating branch currents without full node analysis
- Understanding real-world current sharing
Basic Current Divider Formula (Two Resistors)
For two resistors R1 and R2 connected in parallel
with total current IT:
I1 = IT × (R2 / (R1 + R2)) I2 = IT × (R1 / (R1 + R2))
The branch with lower resistance carries more current.
General Current Divider Formula (Multiple Resistors)
For a resistor Rn in a parallel network:
In = IT × (1 / Rn) / (Σ (1 / Rk))
This form is based on conductance, where conductance
G = 1 / R.
Current Divider Using Conductance
Using conductance simplifies calculations in large networks:
In = IT × (Gn / GT)
where:
Gn= conductance of branch nGT= total conductance of all parallel branches
Current Divider with AC Circuits
In AC circuits, resistance is replaced by impedance Z.
The same principles apply, but impedance may include resistance,
inductive reactance, and capacitive reactance.
In = IT × (1 / Zn) / (Σ (1 / Zk))
Types of Current Dividers
Resistive Current Divider
Uses only resistors. This is the most common and simplest type, widely used in DC and low-frequency AC analysis.
Impedance-Based Current Divider
Uses complex impedance. Found in AC circuits involving inductors and capacitors.
Current Divider with Shunt Resistors
A low-value resistor placed in parallel to divert current. Common in current sensing and measurement circuits.
Active Current Divider
Uses active components such as transistors or op-amps to control current ratios precisely.
Key Assumptions
- All branches share the same voltage
- Ideal components unless stated otherwise
- No significant parasitic effects
Common Mistakes
- Applying current divider rules to series circuits
- Ignoring impedance in AC systems
- Forgetting current divides inversely with resistance