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Simple phenomena of magnetism Study Notes | CIE iGCSE Physics

CIE iGCSE Physics Simple phenomena of magnetism Study Notes -2025-2028 Syllabus

ACIE iGCSE Physics Simple phenomena of magnetism Study Notes

CIE iGCSE Physics Simple phenomena of magnetism Study Notes at  IITian Academy  focus on  specific topic and type of questions asked in actual exam. Study Notes focus on CIE iGCSE Physics syllabus with Candidates should be able to:

Core: –

  1. Describe the forces between magnetic poles and between magnets and magnetic materials, including the use of the terms north pole (N pole), south pole (S pole), attraction and repulsion, magnetised and unmagnetised
  2. Describe induced magnetism
  3. State the differences between the properties of temporary magnets (made of soft iron) and the properties of permanent magnet (made of steel)
  4. State the difference between magnetic and non-magnetic materials
  5. Describe a magnetic field as a region in which a magnetic pole experiences a force.
  6. Draw the pattern and direction of magnetic field lines around a bar magnet
  7. State that the direction of a magnetic field at a point is the direction of the force on the N pole of a magnet at that point
  8. Describe the plotting of magnetic field lines with a compass or iron filings and the use of a compass to determine the direction of the magnetic field
  9. Describe the uses of permanent magnets and electromagnets.

Supplement: –

10. Explain that magnetic forces are due to interactions between magnetic fields

11. Know that the relative strength of a magnetic field is represented by the spacing of the magnetic field lines

CIE iGCSE  Physics Study Notes- All Topics

Magnetic Forces

Magnets exert forces on each other due to their North and South poles. Like poles (North-North or South-South) repel, while opposite poles (North-South) attract. This interaction is mediated by invisible magnetic fields surrounding each magnet.

  • Magnets have two poles: North and South.
  • Like poles repel, opposite poles attract.
  • Magnetic forces arise from interacting magnetic fields.
  • Magnetic materials are attracted to both poles.
  • A magnet has distinct North and South poles.
  • Magnets interact via attraction/repulsion; magnetic materials are simply attracted.

Magnetic Fields

A magnetic field is a region of space surrounding a magnet where a magnetic force is exerted. It’s an invisible force field, analogous to an aura, emanating from the magnet and influencing magnetic materials within its range. Every magnet, regardless of size, generates its own unique magnetic field. This field extends outward from the magnet in all directions, its strength diminishing with increasing distance from the source. We visualize these fields using imaginary constructs called magnetic field lines. These lines provide a representation of both the field’s strength and its direction at any given point in space.

The direction of a magnetic field line is conventionally defined as the direction a north magnetic pole would experience a force. Thus, these lines always originate from the North pole of a magnet and terminate at its South pole, forming closed loops. Think of them as flowing from North to South, both inside and outside the magnet. A crucial characteristic of magnetic field lines is that they never intersect. While they may curve and bend in complex patterns, they always maintain their individual, distinct paths, never crossing one another. The density of the field lines is an indication of the field’s strength; closer lines indicate a stronger field.

Magnetic and Non-Magnetic Materials

A magnetic material is attracted to a magnet, while a non-magnetic material is not, because of the different arrangement of magnetic domains within their structure: magnetic materials have aligned domains that readily respond to a magnetic field, whereas non-magnetic materials have randomly oriented domains, cancelling out any magnetic attraction
 
Key points about magnetic and non-magnetic materials:
 
  • Magnetic materials:
    • Examples: Iron, nickel, cobalt 
       
    • Explanation: When placed near a magnet, the magnetic domains within these materials align themselves, creating a strong magnetic force of attraction. 
       
  • Non-magnetic materials:
    • Examples: Plastic, rubber, wood, glass 
       
    • Explanation: The magnetic domains in non-magnetic materials are randomly oriented, so they don’t experience a significant magnetic force when placed near a magnet. 

Magnetic Induction

Magnetic induction creates a magnet from a magnetic material without contact with a permanent magnet. Stroking a material with a permanent magnet aligns its magnetic domains, inducing magnetism. Passing a DC current through a coil surrounding the material also induces magnetism by aligning domains with the coil’s magnetic field.

Demagnetization can occur through several methods. Hammering a magnet disrupts domain alignment, weakening its magnetic properties. Heating a magnet causes thermal agitation, misaligning domains. Applying and then removing an alternating current creates fluctuating fields, also disrupting domain alignment and leading to demagnetization.

Magnetic induction is a useful process with applications ranging from creating permanent magnets to understanding magnetic storage devices.

Electromagnets

An electromagnet is a coil of wire that acts like a magnet when an electric current passes through itThe magnetic field disappears when the current stops flowing. 
 
How it works
    • Electric currentMoving charges create magnetic fields. 
       
    • CoilThe wire is wrapped into a coil. 
       
  • CoreThe coil is often wrapped around a core made of iron or another magnetic material. This concentrates the magnetic field and makes the magnet stronger. 
     
  • Magnetic fieldThe magnetic field is concentrated along the center of the coil. 
     
  • On and offThe magnetic field can be turned on and off by controlling the electric current. 
     
Uses
  • ElectronicsElectromagnets are used in many electronic devices, such as computers, phones, and memory storage devices. 
     
  • Metal separationElectromagnets are used in magnetic separators to separate metals. 
     
  • MotorsElectromagnets are used in motors, such as those in food processors. 
     
  • Microphones and loudspeakersElectromagnets are used in microphones and loudspeakers. 
     
Advantages 
 
  • Electromagnets can be turned on and off.
  • The magnetic field can be quickly changed by controlling the electric current.

Uses of Permanent and Electromagnets

Permanent magnets and electromagnets are used in a variety of applications, including electric motors, speakers, and medical devices
 
Permanent magnets 
 
    • Electric motorsPermanent magnets are used in electric motors.
    • GeneratorsPermanent magnets are used in generators.
  • Electric acceleratorsPermanent magnets are used in electric accelerators.
  • Magnetic recordingsPermanent magnets are used in magnetic recordings.
  • Headphones and earphonesPermanent magnets are used in headphones and earphones.
  • SmartphonesPermanent magnets are used in smartphones.
  • Television setsPermanent magnets are used in television sets.
Electromagnets 
 
  • SpeakersElectromagnets are used in speakers.
  • Electric bellsElectromagnets are used in electric bells.
  • Electric cranesElectromagnets are used in electric cranes.
  • Magnetic lifting devicesElectromagnets are used in magnetic lifting devices.
  • Medical devicesElectromagnets are used in medical devices.
  • Control switches in relaysElectromagnets are used in control switches in relays.
  • Spacecraft propulsion systemsElectromagnets are used in spacecraft propulsion systems.
  • Induction heatingElectromagnets are used in induction heating.
Electromagnets are able to change the strength of their magnetic field by adjusting the electric current. Permanent magnets, on the other hand, maintain their magnetic properties over a long period of time. 
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