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: –
- 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
- Describe induced magnetism
- State the differences between the properties of temporary magnets (made of soft iron) and the properties of permanent magnet (made of steel)
- State the difference between magnetic and non-magnetic materials
- Describe a magnetic field as a region in which a magnetic pole experiences a force.
- Draw the pattern and direction of magnetic field lines around a bar magnet
- 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
- 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
- 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
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.
- Examples: Iron, nickel, cobalt
- 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.
- Examples: Plastic, rubber, wood, glass
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
How it works
- Electric current: Moving charges create magnetic fields.
- Coil: The wire is wrapped into a coil.
- Electric current: Moving charges create magnetic fields.
- Core: The 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 field: The magnetic field is concentrated along the center of the coil.
- On and off: The magnetic field can be turned on and off by controlling the electric current.
Uses
- Electronics: Electromagnets are used in many electronic devices, such as computers, phones, and memory storage devices.
- Metal separation: Electromagnets are used in magnetic separators to separate metals.
- Motors: Electromagnets are used in motors, such as those in food processors.
- Microphones and loudspeakers: Electromagnets 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
- Electric motors: Permanent magnets are used in electric motors.
- Generators: Permanent magnets are used in generators.
- Electric accelerators: Permanent magnets are used in electric accelerators.
- Magnetic recordings: Permanent magnets are used in magnetic recordings.
- Headphones and earphones: Permanent magnets are used in headphones and earphones.
- Smartphones: Permanent magnets are used in smartphones.
- Television sets: Permanent magnets are used in television sets.
Electromagnets
- Speakers: Electromagnets are used in speakers.
- Electric bells: Electromagnets are used in electric bells.
- Electric cranes: Electromagnets are used in electric cranes.
- Magnetic lifting devices: Electromagnets are used in magnetic lifting devices.
- Medical devices: Electromagnets are used in medical devices.
- Control switches in relays: Electromagnets are used in control switches in relays.
- Spacecraft propulsion systems: Electromagnets are used in spacecraft propulsion systems.
- Induction heating: Electromagnets are used in induction heating.