Edexcel iGCSE Physics -6.9P Construction of Electromagnets- Study Notes- New Syllabus
Edexcel iGCSE Physics -6.9P Construction of Electromagnets- Study Notes- New syllabus
Edexcel iGCSE Physics -6.9P Construction of Electromagnets- Study Notes -Edexcel iGCSE Physics – per latest Syllabus.
Key Concepts:
6.9P describe the construction of electromagnets
Construction of an Electromagnet
An electromagnet is a magnet produced by an electric current. Unlike a permanent magnet, its magnetism can be switched on and off and its strength can be controlled.
Electromagnet – Definition
Definition: An electromagnet is a coil of insulated wire wound around a magnetic core that becomes magnetised when an electric current flows through the wire.
Key idea: The magnetic field is produced by the electric current and disappears when the current is switched off.
Main Parts of an Electromagnet
An electromagnet is constructed using the following components:
- A coil of insulated copper wire
- A soft iron core
- A power supply (battery or DC supply)
- Connecting wires and a switch
Step-by-Step Construction
- Take a soft iron rod or nail.
- Wind insulated copper wire tightly around the iron core to form a coil.
- Ensure the turns are close together and in the same direction.
- Connect the ends of the wire to a power supply.
- Include a switch to control the current.
Result: When current flows, the iron core becomes magnetised and acts as a magnet.
Why Soft Iron Is Used as the Core
- Soft iron is magnetically soft.
- It becomes magnetised easily.
- It loses magnetism quickly when current is switched off.
Key idea: This allows the electromagnet to be turned on and off efficiently.
Magnetic Field of an Electromagnet
- The field pattern is similar to a bar magnet.
- One end behaves as a north pole, the other as a south pole.
- Reversing the current reverses the poles.
Factors That Increase the Strength of an Electromagnet
- Increasing the current through the coil
- Increasing the number of turns of the coil
- Using a soft iron core instead of air
Example
An electromagnet is required for use in a scrapyard crane. Describe how the electromagnet should be constructed and explain why this design is suitable.
▶️ Answer / Explanation
- A coil of insulated wire is wound around a soft iron core.
- The coil is connected to a power supply.
- When current flows, the core becomes magnetised.
- Soft iron loses magnetism when the current is switched off.
- This allows metal objects to be lifted and released easily.
Example
A student replaces the soft iron core of an electromagnet with a steel core. Explain how this affects the operation of the electromagnet.
▶️ Answer / Explanation
- Steel is magnetically hard.
- It does not demagnetise easily.
- The core would remain magnetised after the current is switched off.
- This makes the electromagnet unsuitable where magnetism must be switched off.