IP Physics Electricity and Practical Mastery Guide

Download printable cheat-sheet (CC-BY 4.0)

12 Jun 2025, 00:00 Z

Electricity & Magnetism makes up roughly one-third of examinable content, so exam setters tend to devote a similar share of marks, although SEAB publishes no exact percentage. The practical paper is a fixed 20 % for Pure Physics and H2 Physics (15 % for the Combined-Science track). [9][10][11]
This guide compresses the must-knows into a single page of myth-busting explanations, step-by-step methods and a one-week micro-practice plan.

1 Why electricity + practical skills decide your IP grade

Weightage in written exams - SEAB does not release a marks-by-topic table, but O-level 6091 lists Electricity & Magnetism as 7 of 20 topics (≈ 35 % coverage). A-level H2 shows a comparable fraction, so the oft-quoted “25-35 % of marks” is a reasonable estimate, not an official guarantee. [9][10][11]
Weightage in practicals - The practical component is locked at 20 % for Pure Physics (O-level 6091) and H2 Physics, and 15 % for Combined Science. Most IP tracks follow the 20 % route. [9][10][11]
High misconception rate - Misideas such as "current is used up" or "a battery is a constant-current source" often survive formal teaching.
Sparse free help online - Tuition ads invoke “Kirchhoff nightmares” yet rarely share full worked solutions or uncertainty math.

Miss this cluster and recovery at Promo time is brutal; master it now and the rest of the syllabus feels lighter.

2 Concept mastery - circuits, fields and graphs

2.1 Five killer misconceptions and the one-line fixes

Misconception	Quick fix
Current is lost in a bulb	Charge flows through; energy converts, current stays equal in series.
Higher resistance means less current everywhere	In a divider, the branch with higher R can still get full supply V. Use $I = V / R$.
Battery is a constant-current source	Treat it as a constant emf source; current depends on external R.
Potential rises round the loop	Kirchhoff's loop rule: algebraic sum of drops and rises is zero. Pick a sign convention and stick to it.
Field lines show particle paths	They indicate force on a +test charge, not the trajectory.

2.2 Three-step method for multi-loop circuit problems

Label currents in each branch with clear directions.
Write node equations (KCL).
Write two independent loop equations (KVL) and solve simultaneously.

A worked example with full algebra lives in the downloadable worksheet below.

2.3 Energy model beyond $V = I R$

Picture the circuit as energy hills: emf lifts you up, resistors are slopes. Sketch a quick potential graph around the loop to see voltage division without heavy algebra.

2.4 Graph-question playbook

Transform raw data to the linear form requested, e.g. $1 / I$ vs $R$.
Draw a best-fit line with even scatter above and below.
Gradient reveals the physical constant; intercept often exposes internal resistance.

3 Practical skills - stopwatch to uncertainty table

3.1 Four-minute clean setup

Clamp meters so your eye meets the scale perpendicularly.
Run leads along bench edges to avoid loops that pick up noise.
Zero all instruments, then restart the stopwatch.

These steps wipe out the common MMO penalties flagged in the SEAB rubric.

3.2 Data-logger hacks the rules allow

Use on-board averaging to tame probe flicker.
Save as CSV, not proprietary formats, so you can re-plot instantly if an examiner asks.

3.3 The 1-2-5 rule for uncertainty

Record every raw reading with its instrument precision, then round absolute uncertainty to 1, 2 or 5 x 10^n.

3.4 Sample full-mark graph

$R / Ω$	$I / A$
1.0	0.190
2.2	0.126
3.3	0.090
4.7	0.065

Plot $I$ on the y-axis, $1 / R$ on the x-axis.
Gradient ≈ emf.
Add one small error bar per point to show ±uncertainty.

4 One-week micro-practice plan

Day	15-min mission	Habit reinforced
Mon	Derive node + loop equations for a two-battery circuit	Self-explain each step
Tue	Redraw yesterday's circuit as a potential graph	Sketch-symbol-sentence loop
Wed	Timed practical: set up a potential divider, measure $V$ vs $R$	Four-minute setup
Thu	Calculate percentage uncertainty and comment on result validity	Uncertainty log
Fri	Mixed retrieval: 5 MCQs on fields, series, parallel, emf	Retrieval roulette
Sat	Write one variation of each MCQ and solve it	One-knob variation
Sun	Record a 90-s Feynman video explaining internal resistance	Spaced teaching

5 FAQ

What formulas must I memorise?
Only $ V = I R $, $ P = I V $, $ Q = I t $, Kirchhoff's laws and the potential-divider equation. Everything else derives on the fly. [1]

How is Paper 3 marked?
15 % of the final grade, split across planning, MMO, PDO and ACE as per SEAB. [2][3]

Do digital meters remove the need for reading uncertainty?
No. Quote $\pm\frac{1}{2}$ least count or the manufacturer spec. [4][5]