Rules for current and p.d. in series and parallel circuits, combining resistors in series and parallel, and solving series–parallel circuit problems.
5 narrated scenes. Press play, listen and read along — the points appear as they are explained. Use ‹ Prev / Next › or the scene bar to jump to any scene.
Christmas lights used to fail all at once when one bulb blew; modern strings keep shining. The difference is series versus parallel.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Copy these into your notebook in your own words — that is how they stick.
Same I; V adds; R_s = R₁ + R₂ + R₃.
Same V; I adds; 1/R_p = 1/R₁ + 1/R₂ + ….
R_p = R₁R₂ ÷ (R₁ + R₂).
Carries the larger current in parallel.
Always less than the smallest branch.
Combine parallel parts, add series, find I, then p.d.s and branch currents.
V = IR applies to every part and to the whole circuit.
In parallel so each appliance has full voltage and works independently.
3 quick games on this lesson. Earn XP and badges as you play — your best score for each game is saved. Games are for practice and do not change your exam readiness. More games in the Physics Arcade.
8 items modelled on real CSEC Paper 1 questions. Choose one answer for each, then check. Aim for 80% or better. Work each item on paper first.
Write full answers, then reveal the mark scheme and tick the points you earned (17 marks in total). Show all your working — method marks count. Your answers are saved on this device.
Question 1 [17 marks]
A 12 V battery is connected to a 4.0 Ω resistor in series with a parallel combination of 6.0 Ω and 3.0 Ω resistors.
(a) (a) Draw the circuit diagram. [3]
(b) (b) Calculate the combined resistance of the parallel pair. [3]
(c) (c) Calculate the total resistance of the circuit. [2]
(d) (d) Calculate the current from the battery. [3]
(e) (e) Calculate the p.d. across the parallel pair. [3]
(f) (f) Calculate the current in the 3.0 Ω resistor. [2]
(g) (g) State one reason why household appliances are connected in parallel. [1]
Find these in your own past-paper booklets for extra timed practice. Items above are written in the style of these papers; any adapted from a specific question say so.