(a) State any two advantages of connecting electrical appliances in parallel rather than in series in a domestic circuit.
(b) Three identical bulbs are connected in parallel across a 12 V source and the total current drawn is 3 A. Calculate the resistance of each bulb.
Generated by claude-sonnet-4-6 · 2026-06-26 01:09 · grounding rag
Model Answer
(a) Two advantages of parallel connection in domestic circuits:
- Each appliance gets the same (full) voltage of the supply, so they work at their rated capacity.
- If one appliance fails, the others continue to work as each branch is an independent path.
(b) In parallel, voltage across each bulb = 12 V; total current = 3 A.
Since bulbs are identical, current through each bulb:
$$I_{each} = \frac{3}{3} = 1 \text{ A}$$
By Ohm's law, resistance of each bulb:
$$R = \frac{V}{I} = \frac{12}{1} = 12 \text{ Ω}$$
The resistance of each bulb is 12 Ω.
Source: Electricity, Section 11.6.2 (Resistors in Parallel)
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Explanation
- For part (a), examiners expect two distinct points — full/equal voltage to each device and independent operation. Either of these plus one more (e.g., easy to add/remove appliances, lower equivalent resistance) scores full marks.
- For part (b), the key insight is: identical bulbs in parallel share the total current equally. Once you find current per bulb (1 A), a simple V = IR calculation gives the answer. Show all steps clearly for full credit.