Explain the advantages of connecting lamps in parallel in a lighting circuit
4.3.2 Series and Parallel Circuits
What is a Parallel Circuit?
In a parallel circuit, each component (like a lamp) is connected across the same two points, so every lamp gets the full supply voltage. Think of it as a group of roads branching from a main highway – each road starts and ends at the same two points, so traffic (current) can flow independently on each road. 🚗💡
Key Formulae
Ohm’s law: $V = IR$ Total resistance in parallel: $\displaystyle \frac{1}{R_{\text{total}}} = \frac{1}{R_1} + \frac{1}{R_2} + \dots$ Current through one lamp: $I_{\text{lamp}} = \frac{V_{\text{supply}}}{R_{\text{lamp}}}$
Series vs. Parallel – Quick Comparison
| Feature | Series | Parallel |
|---|---|---|
| Voltage across each lamp | Divides – each lamp gets less than the supply | Same as supply – each lamp gets full voltage |
| Current through each lamp | Same current flows through all lamps | Each lamp draws its own current |
| Effect of a lamp burning out | All lamps go out (open circuit) | Only that lamp goes out; others keep working |
Why Connect Lamps in Parallel? 🔌💡
- Consistent Brightness: Every lamp receives the full supply voltage, so they all shine at the same brightness.
- Independent Operation: If one lamp burns out, the others keep lighting up – no total blackout.
- Easy Replacement: Swap out a single lamp without affecting the rest of the circuit.
- Safety: Lower risk of overloading a single path; current splits across multiple paths.
Real‑World Analogy 🌆
Picture a city street with streetlights. In a parallel layout, each streetlight is wired directly to the power source. If one light fails, the others stay lit, keeping the street safe. In a series layout, all lights would be on a single line; if one fails, the whole line goes dark – not ideal for safety or convenience. 🚦
Revision
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