Series Resistors and Voltage Division
For resistors connected end-to-end with no branching node, equivalent resistance is their sum. With an unloaded divider, each voltage drop is proportional to its resistance.
Why this shows up in the exam
Voltage-divider design · Series heater or lamp circuits · Combining wire segments
Learn the idea
Series elements carry the same current and their voltage drops add. A single stream of charge passes through every series resistor. A larger resistance therefore claims a larger share of the total voltage.
🧠 Memory hook: Same current in series; voltage divides by resistance.
Get this one clearly and it pays off every single time it shows up in the paper. 🎯
Formulas & facts to keep ready
- R_eq = sum R_i — series equivalent resistance
- V_i = V R_i/(sum R) — unloaded voltage divider across series resistors
How to approach it
- 1Confirm there is no branch at the shared node
- 2Add series resistance
- 3Use the common current or voltage ratio
Common slip-ups that cost marks
- •Using voltage division when a load creates a branch
- •Adding conductances in series
- •Assuming equal drops across unequal resistors
🌟 That's the whole idea — you've got this. Try the practice set below; every question you attempt makes it stick a little harder.
Original chapter practice
Original questions for this chapter, not past-paper questions or an exact mapping to this individual concept.
A cell of emf 6 V and internal resistance 1 ohm is connected to a 2 ohm resistor. Find the circuit current.
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