The straight wire, the coil centre and the solenoid kept apart; the Lorentz force, circular motion and the velocity selector; BIL, parallel wires, coil torque and the Hall voltage.
Unit 4 carries 9 of the 50 physics marks; with seven chapters sharing them, this one averages a little over one (MEC publishes weights by unit, not by chapter) — but it is the densest chapter in the unit, with three scope points and half a dozen formulae that look alike. It is also the most numerical, so it repays practice more than any other chapter here.
The MEC scope lines are: B-field around a straight conductor, a circular coil and a long solenoid; Force on a moving charge and on a current-carrying conductor or coil in a uniform field; Hall effect. The headings below are those points, in MEC's order.
Three ways it is asked: recall (the direction rule for a straight wire, what the Hall effect reveals about the carriers, the formula for the field at the centre of a coil); understanding (why a magnetic force can never change a particle's speed, why the period of a charged particle in a field does not depend on its speed, why parallel currents in the same direction attract); application (a field at a stated distance from a wire, a radius r = mv/qB, the force per metre between two wires, the torque on a galvanometer coil, a Hall voltage).
Upgrade to unlock this and every premium study note, formula sheet and high-yield summary — plus unlimited mocks and full solutions.
See the plansCurrent Electricity and Magnetism: Unit Map and Reading Order
What the Current electricity and magnetism unit covers, how many of the 50 Physics questions it carries, and the order to read its seven chapter notes in.
Physics Formula Sheet — Rapid Revision
Every Physics relation on the MECEE-BL blueprint on one page: mechanics, heat, waves and optics, electricity and magnetism, modern physics — with the constants and unit traps that cost marks.
Physical Quantities, Vectors and Scalars: Units, Errors, Resultants
SI units and prefixes, precision against accuracy, significant-figure arithmetic, error combination, the dimensional formulae that get asked, and every vector law from the parallelogram to the river crossing.
Kinematics: Motion Graphs, Free Fall and the Projectile
The three equations of motion, what every slope and area on a motion graph means, free-fall and relative-motion numericals, the full projectile set, and what air resistance does to all of it.