OCR · GCSE · Physics
Course version: J249 · Version from Sept 2018
Describe the attraction and repulsion between unlike and like poles for…
Full specification wording
Magnets and magnetic fields: describe the attraction and repulsion between unlike and like poles for permanent magnets (to include: diagrams of magnetic field patterns around bar magnets to show attraction and repulsion)
A permanent magnet has two poles, north and south, and the rule is simple: unlike poles attract and like poles repel.
Checked against the OCR J249 specification (opens in a new tab) on .
- Point 1 of 7
- 3 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
A permanent magnet has two poles, north and south, and the rule is simple: unlike poles attract and like poles repel. Bring a north pole near a south pole and the magnets pull together; bring two north poles (or two south poles) near each other and they push apart. You can show this with field-line diagrams. Field lines leave a north pole and enter a south pole, and they never cross. For two attracting bar magnets placed end to end, the lines run from the north pole of one across the gap into the south pole of the other, showing the pull. For two repelling magnets with like poles facing, the lines curve away from each other and do not join across the gap, showing the push. The closer the lines, the stronger the field. A question may ask you to pick the correct statement or the correct diagram, so check both the pole labels and the direction of the arrows.
What earns the marks
- States that unlike poles (north and south) attract each other.
- States that like poles (north and north, or south and south) repel each other.
- Identifies a field-line diagram in which lines run from a north pole across the gap into a south pole as showing attraction.
- Identifies a field-line diagram in which lines curve away from like poles without joining across the gap as showing repulsion.
- Recognises that magnetic field lines leave a north pole and enter a south pole and never cross.
Common mistakes and how to put them right
Claims that two north poles attract each other.
Put it right by stating that like poles repel.
Reads a diagram with lines joining across the gap as repulsion.
Put it right by noting that joining lines from north to south show attraction.
Assumes field lines cross where two fields meet.
Put it right by stating that field lines never cross.
Exam tips
- Read the pole labels on each diagram before choosing, because the same picture can show attraction or repulsion depending on which poles face each other.
- Check the arrow direction: lines leave a north pole and enter a south pole.
- Eliminate options that say like poles attract or unlike poles repel, since these reverse the rule.
Try the lesson
The start of the Magnets and magnetic fields: describe the attraction and repulsion between unlike and like poles for permanent magnets (to include: diagrams of magnetic field patterns around bar magnets to show attraction and repulsion) lesson, made from checked teaching notes for this specification point.
Have a go first
A south pole is brought towards the north pole of a hanging bar magnet. What is observed?
Listen
A permanent magnet has two poles, north and south, and the rule is simple: unlike poles attract and like poles repel. Bring a north pole near a south pole and the magnets pull together; bring two north poles (or two south poles) near each other and they push apart. You can show this with field-line diagrams. Field lines leave a north pole and enter a south pole, and they never cross. For two attracting bar magnets placed end to end, the lines run from the north pole of one across the gap into the south pole of the other, showing the pull. For two repelling magnets with like poles facing, the lines curve away from each other and do not join across the gap, showing the push. The closer the lines, the stronger the field. A question may ask you to pick the correct statement or the correct diagram, so check both the pole labels and the direction of the arrows. A strong answer earns marks for these points. States that unlike poles (north and south) attract each other. States that like poles (north and north, or south and south) repel each other. Identifies a field-line diagram in which lines run from a north pole across the gap into a south pole as showing attraction. Identifies a field-line diagram in which lines curve away from like poles without joining across the gap as showing repulsion. A common slip: Claims that two north poles attract each other. Instead, stating that like poles repel. Exam tip: Read the pole labels on each diagram before choosing, because the same picture can show attraction or repulsion depending on which poles face each other.
Key words
Say what each word means before you turn the card.
Magnetic poles
Try answering aloud or in your head before turning the card.
Attraction and repulsion
Try answering aloud or in your head before turning the card.
Magnetic field patterns
Try answering aloud or in your head before turning the card.
See every definition
- Magnetic poles
- A permanent magnet has two poles, north and south, and the rule is that unlike poles attract and like poles repel.
- Attraction and repulsion
- Unlike poles attract and like poles repel, so a north pole near a south pole pulls together while two north poles push apart.
- Magnetic field patterns
- Field lines leave a north pole and enter a south pole and never cross, and the closer the lines the stronger the field.
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