Series Circuit Examples in Physics

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Series Circuit.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Physics.

Concept Recap

A circuit in which components are connected end-to-end, so the same current flows through each one.

Like cars on a single-lane road — every car (charge) must pass through every toll booth (component) in order.

Read the full concept explanation →

How to Use These Examples

  • Read the first worked example with the solution open so the structure is clear.
  • Try the practice problems before revealing each solution.
  • Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Same current everywhere, but voltage splits across components proportionally to their resistance.

Common stuck point: Adding more resistors in series increases total resistance and decreases current.

Worked Examples

Example 1

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Three resistors (4 \text{ } \Omega, 6 \text{ } \Omega, 10 \text{ } \Omega) are connected in series to a 20 \text{ V} battery. What is the current and the voltage across each resistor?

Solution

  1. 1
    Total resistance: R_T = 4 + 6 + 10 = 20 \text{ } \Omega.
  2. 2
    Current (same through all): I = \frac{V}{R_T} = \frac{20}{20} = 1 \text{ A}
  3. 3
    Voltage drops: V_1 = IR_1 = 4 \text{ V}, V_2 = IR_2 = 6 \text{ V}, V_3 = IR_3 = 10 \text{ V}.
  4. 4
    Check: 4 + 6 + 10 = 20 \text{ V} (matches battery voltage).

Answer

I = 1 \text{ A}; \quad V_1 = 4 \text{ V}, V_2 = 6 \text{ V}, V_3 = 10 \text{ V}
In a series circuit, current is the same through all components. Resistances add directly, and the battery voltage divides among the resistors proportionally to their resistances.

Example 2

hard
A 6 \text{ V} battery powers a series circuit with a 3 \text{ } \Omega resistor and an unknown resistor. The current is 0.5 \text{ A}. Find the unknown resistance and the power dissipated by each resistor.

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

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Two resistors in series have a total resistance of 15 \text{ } \Omega. If one is 7 \text{ } \Omega, what is the other?

Example 2

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Three resistors (4 \text{ } \Omega, 6 \text{ } \Omega, and 2 \text{ } \Omega) are connected in series to a 24 \text{ V} battery. Calculate: (a) total resistance, (b) current, (c) voltage across the 6 \text{ } \Omega resistor.
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Background Knowledge

These ideas may be useful before you work through the harder examples.

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