54. Series Circuits

1. Potential Difference (Voltage)

In a series circuit, the total potential difference provided by the power source (cell or battery) is shared across all the components.

• The Rule: V_Total = V₁ + V₂ + ...

• Example: If you have a 12V battery and two lamps, the voltages across those two lamps must add up to 12V.

• Distribution: Components with a higher resistance will take a larger share of the total potential difference. If two components are identical, they will share the voltage equally.

2. Current

Current is the same everywhere in a series circuit. It doesn't matter where you place an ammeter; the reading will be identical.

• The Rule: I_Total = I₁ = I₂ = ...

• Measurement: We use an ammeter to measure current, which is always placed in series (within the main loop).

• Calculation: You can find the current using Ohm's Law: I = V_Total / R_Total.

3. Resistance

The total resistance of a series circuit is simply the sum of the resistances of each individual component.

• The Rule: R_Total = R₁ + R₂ + ...

• Example: If one lamp has a resistance of 4Ω and another has 2Ω the total resistance is 6Ω.

4. Measuring and Calculating Values

Using a Voltmeter

To measure the potential difference across a specific component, you must connect a voltmeter in parallel across that component. Even though the voltmeter is in parallel, the circuit itself is still considered a series circuit.

Calculating Individual Voltage

You can calculate the voltage across a specific component if you know the current flowing through it and its resistance:

• Formula: V = IR

• Example: If 2A is flowing through a 4Ω resistor, that component uses 8V of the potential difference (2 x 4 = 8).

5. Summary Table for Series Circuits