IB MYP 4-5 Physics- Electromagnets and their applications- Study Notes - New Syllabus
IB MYP 4-5 Physics-Electromagnets and their applications- Study Notes
Key Concepts
- Electromagnets and their applications
Electromagnets and Their Applications
Electromagnets and Their Applications
Electromagnet
An electromagnet is a temporary magnet made by passing electric current through a coil of wire wound around a soft iron core.
- When current flows → coil produces a magnetic field → soft iron core becomes magnetized.
- When current stops → magnetism disappears (unlike permanent magnets).
- Strength of an electromagnet depends on:
- Magnitude of current (more current → stronger field).
- Number of turns of coil (more turns → stronger field).
- Type of core (soft iron is best, as it is easily magnetized and demagnetized).
Advantages of Electromagnets
- Can be switched on and off easily.
- Strength can be controlled by adjusting current.
- Produce much stronger magnetic fields compared to permanent magnets of similar size.
Applications of Electromagnets
- Electric bells: Electromagnet pulls a hammer to strike the bell repeatedly.
- Relays & switches: Used to open/close circuits automatically.
- Electric motors & generators: Convert electrical ↔ mechanical energy.
- Cranes: To lift heavy scrap iron/steel in junkyards.
- Medical uses: MRI scanners, removing iron splinters from wounds.
- Loudspeakers: Vibrating electromagnet produces sound waves.
Example:
A student makes an electromagnet by wrapping 100 turns of wire around a soft iron core and passing 2 A of current. How can the strength of this electromagnet be increased?
▶️ Answer/Explanation
Step 1: Strength depends on number of turns, current, and core material.
Step 2: To increase strength, student can:
(i) Increase number of turns.
(ii) Increase current.
(iii) Use a larger/softer iron core.
Final Answer: Strength increases by more turns, higher current, or better core material.
Example:
Why are electromagnets preferred over permanent magnets in cranes used to lift scrap metal?
▶️ Answer/Explanation
Step 1: Permanent magnets cannot be switched off → they would hold onto the scrap continuously.
Step 2: Electromagnets can be turned off after lifting to drop the load easily.
Step 3: Electromagnet strength can be varied to lift small or large amounts of scrap.
Final Answer: Electromagnets are controllable and switchable, making them more useful for cranes.
Example:
A patient has a tiny iron splinter stuck in their eye. Explain how an electromagnet can help remove it safely.
▶️ Answer/Explanation
Step 1: A small electromagnet can be brought close to the eye.
Step 2: Current switched on → electromagnet attracts the iron splinter.
Step 3: Current switched off → magnetism disappears, allowing safe removal.
Final Answer: Electromagnet allows precise and temporary magnetic action to remove splinters.