Poles and magnetic materials
Between two magnets: like poles repel (N-N or S-S push apart) and unlike poles attract (N-S pull together). Between a magnet and a magnetic material: a magnet only ever attracts an unmagnetised magnetic material — it can never repel it. The magnetic materials are iron, steel, cobalt and nickel; most metals (copper, aluminium) and all non-metals are not magnetic. So attraction alone never proves an object is a magnet — only repulsion does.
Hard vs soft magnetic materials
Magnetically hard materials (e.g. steel) are difficult to magnetise and difficult to demagnetise, so they keep their magnetism — used for permanent magnets. Magnetically soft materials (e.g. iron) are easy to magnetise and easy to demagnetise, so they lose their magnetism the moment the field is removed — used for electromagnet cores. "Hard" and "soft" describe magnetic behaviour, not how bendy the metal is.
Field lines and uniform fields
A magnetic field is the region where a magnet or magnetic material feels a force, drawn as field lines. Outside the magnet the arrows point from north to south (N S). Lines never cross, and the field is stronger where they are closer together (strongest at the poles). A uniform field — same strength and direction everywhere — is drawn as equally spaced parallel lines, as found in the gap between an N pole facing an S pole.
Drawn from real examiner reports.
Field-line arrows: N to S, no crossing
Field-pattern diagrams are marked strictly on arrows and spacing. Arrows must point from north to south outside the magnet; arrows the wrong way, or contradicting arrows on one diagram, lose the direction mark. Lines must never cross and must start and end on the poles, meeting the magnet at right angles.
Jun 2024 1P Q6a: most drew arrows towards the south pole; marks were lost for contradicting or wrong-direction arrows.
Strength = spacing, not length
When asked how a diagram shows where the field is strongest, the only credited idea is the spacing of the lines: stronger where they are closer together, weaker where further apart. Describing lines as "longer", "bigger", "thicker" or "more curved" earns nothing — length and curviness say nothing about field strength.
Jun 2024 1P Q6c: weaker candidates linked field strength to the size, length or curviness of the lines and lost the marks.
Space field lines evenly; don't overcrowd
Because spacing carries the meaning (closer = stronger), the lines you draw must be evenly spaced for a given region. Adding too many lines, or drawing uneven gaps where the field is actually uniform, loses the mark. Draw just enough lines to show the pattern, at consistent gaps — sloppy or overcrowded spacing sends the wrong message about field strength.
Nov 2024 1P Q5a: adding too many field lines with uneven gaps lost the mark; equal spacing was required.
Induced magnetism: name the induced pole
For "why is the iron attracted?", a bare "the magnet attracts iron" scores nothing. Induced magnetism means the iron, placed in the field, becomes a magnet: an opposite pole is induced on the end nearest the magnet. These are now unlike poles, so they attract. Name the induced pole and the unlike-poles-attract step; label the diagram if invited.
Jun 2024 1P Q6d(i): over half scored nothing; the marks came from naming the INDUCED north pole on the iron and labelling the diagram.
"Soft magnet"/"soft metal" loses marks
Describing a soft magnetic material as a "soft metal" or "soft magnet" loses marks. "Soft" and "hard" are about magnetic behaviour, not how bendy the metal is: a soft material (iron) loses its magnetism once removed from the field, while a hard material (steel) keeps it. State the behaviour when the field is removed, not the everyday meaning of "soft".
Jun 2024 1P Q6d(ii): weaker candidates wrote loosely about "soft metals"/"soft magnets" instead of the iron losing its magnetism outside the field.
Attraction never proves a magnet
A magnet attracts any magnetic material, magnetised or not, so attraction alone never proves an object is a magnet — it could be unmagnetised steel. Only repulsion proves it, because repulsion happens only between two magnets with like poles facing. If a test shows attraction, stay uncertain; if it shows repulsion, both objects must be magnets.
Copper and aluminium are NOT magnetic
Only iron, steel, cobalt and nickel are magnetic materials attracted by a magnet. Common wrong choices are copper and aluminium (both non-magnetic metals) and non-metals such as plastic. Note too that a magnetic material can be attracted or magnetised, but that does not make it a magnet — a magnet already has permanent N and S poles.
Prove a magnet by repulsion
To decide whether an object is a magnet, look for repulsion, not attraction. A magnet attracts any magnetic material, so attraction is inconclusive; repulsion needs two magnets with like poles facing, so it is the only proof.
Field diagrams: N to S, judge by spacing
Draw arrows N S outside, lines that never cross, and lines closer together at the poles. Judge field strength only by the spacing of the lines, never by their length or curviness, and keep the spacing even for a uniform field.
Induced magnetism: name the pole
State that a pole is induced in the material, name it (e.g. induced north pole), then apply unlike poles attract. If the question says you may label the diagram, label the induced pole — it is the clearest route to the marks.
Reveal a field: compass for direction
Use a plotting compass to trace a field line and show its direction (the needle's north end points along the field). Iron filings quickly show the field's shape but not its direction — so a compass is still needed to add the arrows.
Magnetism in 4SD0 is a describe-and-draw topic: there are no equations to learn here. Marks come from precise definitions, correctly drawn field lines, and explaining attraction through induced poles.
Define a magnetically HARD material and give an example.
(a) State what happens when the north pole of one magnet is brought near the north pole of another magnet.
(b) Name two materials, other than iron, that are attracted by a magnet.
(c) A student says: "The paperclip is attracted to the bar, so the bar must be a magnet." Explain why this reasoning is not reliable.
