Magnets and magnetic fields (P3.3) | OCR GCSE Combined Science A (Gateway Science) — Physics — Higher (J250)

P3.3 Magnets and magnetic fields

Summary Having an understanding of the flow of charge and its effects, we can now consider the links between movement of charge and magnetism. To begin, learners will investigate magnets and magnetic fields around magnets and current-carrying wires. Underlying knowledge and understanding Learners should have been introduced to magnets and the idea of attractive and repulsive forces. They should have an idea of the shape of the fields around bar magnets. Learners are expected to have an awareness of the magnetic effect of a current and electromagnets.

Common misconceptions Learners hold the misconception that larger magnets will always be stronger magnets. They also have difficulty understanding the concept of field line density being an indicator of field strength. Learners often do not know that the geographic and magnetic poles are not located in the same place.

Reference	Mathematical learning outcomes	Maths skills
$PM3.3i$	$\text{force (N)}=\text{magnetic flux density (T)}\times\text{current (A)}\times\text{length (m)}$

Learning outcomes	To include	Maths	Working scientifically	Practical suggestions
$P3.3a describe the attraction and repulsion between unlike and like poles for permanent magnets$	$diagrams of magnetic field patterns around bar magnets to show attraction and repulsion$		$WS1.1b, WS1.2a, WS1.2b, WS2a, WS2b$	$Using suspended magnets to show attraction and repulsion.$
$P3.3b describe the difference between permanent and induced magnets$
$P3.3c describe the characteristics of the magnetic field of a magnet, showing how strength and direction, change from one point to another$	$diagrams to show attraction and repulsion and also depict how the strength of the field varies around them and ways of investigating this$	$M5b$	$WS1.1b, WS1.2a, WS1.2b, WS2a, WS2b, WS2c$	$Plotting of magnetic fields and use of dipping compass.$
$P3.3d explain how the behaviour of a magnetic (dipping) compass is related to evidence that the core of the Earth must be magnetic$
$P3.3e describe how to show that a current can create a magnetic effect and describe the directions of the magnetic field around a conducting wire$			$WS1.1b, WS1.2a, WS1.2b, WS2a, WS2b, WS2c$	$Investigation of the magnetic field around a current-carrying wire using plotting compasses.$
$P3.3f recall that the strength of the field depends on the current and the distance from the conductor$
$P3.3g explain how solenoid arrangements can enhance the magnetic effect$			$WS1.1b, WS1.2a, WS1.2b, WS2a, WS2b, WS2c, WS2d$	$Investigation of the magnetic field around a current-carrying solenoid using plotting compasses. Investigation of factors that can affect the magnetic effect e.g. number of turns and length.$
$P3.3h describe how a magnet and a current-carrying conductor exert a force on one another$			$WS1.1b, WS1.1e, WS1.2a, WS1.3e$	$Demonstration of the jumping wire experiment.$
$P3.3i show that Fleming’s left-hand rule represents the relative orientations of the force, the current and the magnetic field$
$P3.3j apply the equation that links the force on a conductor to the magnetic flux density, the current and the length of conductor to calculate the forces involved$		$M1a, M1b, M1d, M2a, M3a, M3b, M3c, M3d$
$P3.3k explain how the force exerted from a magnet and a current-carrying conductor is used to cause rotation in electric motors$	$an understanding of how electric motors work but knowledge of the structure of a motor is not expected$		$WS1.1e, WS1.3e, WS2a$	$Construction of simple motors.$

Learning outcomes

To include

Maths

Working scientifically

Practical suggestions

P3.3a describe the attraction and repulsion between unlike and like poles for permanent magnets

diagrams of magnetic field patterns around bar magnets to show attraction and repulsion

WS1.1b, WS1.2a, WS1.2b, WS2a, WS2b

Using suspended magnets to show attraction and repulsion.

P3.3b describe the difference between permanent and induced magnets

P3.3c describe the characteristics of the magnetic field of a magnet, showing how strength and direction, change from one point to another

diagrams to show attraction and repulsion and also depict how the strength of the field varies around them and ways of investigating this

M5b

WS1.1b, WS1.2a, WS1.2b, WS2a, WS2b, WS2c

Plotting of magnetic fields and use of dipping compass.

P3.3d explain how the behaviour of a magnetic (dipping) compass is related to evidence that the core of the Earth must be magnetic

P3.3e describe how to show that a current can create a magnetic effect and describe the directions of the magnetic field around a conducting wire

WS1.1b, WS1.2a, WS1.2b, WS2a, WS2b, WS2c

Investigation of the magnetic field around a current-carrying wire using plotting compasses.

P3.3f recall that the strength of the field depends on the current and the distance from the conductor

P3.3g explain how solenoid arrangements can enhance the magnetic effect

WS1.1b, WS1.2a, WS1.2b, WS2a, WS2b, WS2c, WS2d

Investigation of the magnetic field around a current-carrying solenoid using plotting compasses. Investigation of factors that can affect the magnetic effect e.g. number of turns and length.

P3.3h describe how a magnet and a current-carrying conductor exert a force on one another

WS1.1b, WS1.1e, WS1.2a, WS1.3e

Demonstration of the jumping wire experiment.

P3.3i show that Fleming’s left-hand rule represents the relative orientations of the force, the current and the magnetic field

P3.3j apply the equation that links the force on a conductor to the magnetic flux density, the current and the length of conductor to calculate the forces involved

M1a, M1b, M1d, M2a, M3a, M3b, M3c, M3d

P3.3k explain how the force exerted from a magnet and a current-carrying conductor is used to cause rotation in electric motors

an understanding of how electric motors work but knowledge of the structure of a motor is not expected

WS1.1e, WS1.3e, WS2a

Construction of simple motors.

Magnets and magnetic fields

Next Steps

Learning Objectives