50 lamps, each of resistance 8.0 Ω8.0\ \Omega8.0 Ω, are connected in series to a 200 V200\text{ V}200 V supply in order to decorate a tree.
Calculate:
(i) the current in each lamp,
(ii) the power dissipated in each lamp.
The lamps are designed to "fail-short". If a filament fails, the lamp shorts so that it has no resistance. The other lamps continue to light and the current increases.
The lamps are connected through a fuse that blows when the current rises above 0.65 A0.65\text{ A}0.65 A. At this current, the resistance of each lamp is 10%10\%10% greater than its normal working resistance.
Calculate the maximum number of lamps that can fail before the fuse blows.
52 exam-style questions on CIE IGCSE Physics 4.3.2a Series circuits. Each one has a worked solution and a mark scheme showing where the marks go.