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Lifting Electromagnets
- Lifting electromagnets are very strong electromagnets.
- They are hung from cranes in factories and scrap yards.
- Switch the current ON and the magnet lifts iron objects.
- Switch it OFF and the objects are released.
Example 1 — In a Scrap Yard
- A crane magnet is switched ON.
- It lifts heavy iron scrap easily.
- So the lifting electromagnet moves heavy metal.
Example 2 — Dropping the Load
- The operator switches the current OFF.
- The magnetic field disappears at once.
- So the iron objects are released.
Important Points
- The operator controls the magnet by switching the current ON and OFF.
- They are used to move, lift, and sort heavy metal items.
Definition — Lifting Electromagnet
A lifting electromagnet is a strong electromagnet hung from a crane, used to lift and sort heavy iron or steel objects.
⭐ A Step Further — Electricity and Magnetism
Electric current through a wire makes a magnetic field around it.
In higher grades you will learn that a moving magnet can also make an electric current. This link is the basis of electric motors and power generators.
🧠 Test Yourself — Section 4.1
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Why does a compass needle deflect near a current carrying wire?
View Answer
Because the current makes a magnetic field around the wire, which moves the needle. -
What is an electromagnet?
View Answer
A current carrying coil that behaves like a magnet, usually with an iron core. -
How can you make an electromagnet stronger?
View Answer
Use more current, more coil turns, or add an iron core inside the coil. -
How can you reverse the poles of an electromagnet?
View Answer
By reversing the direction of the current in the coil. -
Where are lifting electromagnets used?
View Answer
In factories and scrap yards, to lift and sort heavy iron and steel.
📋 NCERT Question 2 — True or False statements
Say True or False: dry cells are less portable than Voltaic cells; a coil is an electromagnet only with current; a single cell attracts more clips than two cells.
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📋 NCERT Question 7 — Compass near the coil
Show the current path on the diagram, explain why the compass needle moves, and predict what happens if the battery terminals are reversed.
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📋 NCERT Question 8 — Lifting magnet stops lifting
The switch is left ON; later the nail no longer lifts clips but the wire is still warm. Why did the lifting electromagnet stop working?
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📋 NCERT Question 10 — Coil with the nail removed
If the iron nail is slid out, leaving only the coil, will it still deflect the compass? Will the deflection be more or less?
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📋 NCERT Question 11 — Four coils of different metals
Coils of iron, copper, aluminium, and nichrome are connected to cells. In which circuits will a nearby compass needle deflect?
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