Case Study:

At a large scrap yard near an automobile recycling plant, workers use a giant crane fitted with a powerful circular magnet to lift crushed cars and metal sheets. During one shift, a student visiting the yard noticed something surprising. The crane easily lifted heavy iron car parts weighing more than 500 kg, but nearby plastic buckets and wooden boxes remained completely unaffected, even when they touched the same metal hook.

The crane operator explained that the lifting system works using an electromagnet. Inside the crane’s magnet, electric current passes through a coil of insulated wire wound around a soft iron core. If you've ever wondered about the 'why' behind this, you can explore the fundamental science of how electricity creates magnetism to see how these invisible forces interact. As soon as current flows, a strong magnetic field is produced around the coil. This magnetic field temporarily turns the iron core into a powerful magnet capable of attracting magnetic materials like iron and steel.

This setup is the perfect real-world example of what an electromagnet is and how it’s used across various industries.

The operator also demonstrated that when the electric current was switched off, the lifted metal pieces immediately fell back to the ground. Interestingly, aluminium cans and plastic containers nearby were not attracted at all. The crane consumed nearly 200 A of current during operation to create a strong enough magnetic field for lifting heavy scrap.

The students then discussed an important question: if the crane’s hook touches both metal and plastic objects, why does it attract only certain materials? The answer lies in understanding magnetic materials and how electric current creates a magnetic field inside an electromagnet.

CASE-BASED QUESTIONS

 MCQ 

Q1. Why was the crane able to lift crushed cars but not plastic buckets?
A. Plastic is heavier than iron
B. Plastic blocks electric current
C. Plastic is a non-magnetic material
D. Plastic melts near magnets

Q2. What produces the magnetic field inside the crane’s electromagnet?
A. Heat energy
B. Flow of electric current through the coil
C. Rotation of the crane
D. Friction between metals

 Assertion – Reason 

Q3. Assertion (A): The scrap crane stops attracting metal objects when electric current is switched off.
Reason (R): An electromagnet produces magnetism only when electric current flows through its coil.
A. Both A and R are true, and R is the correct explanation of A
B. Both A and R are true, but R is not the correct explanation of A
C. A is true, but R is false
D. A is false, but R is true

 Application - Based 

Q4. The crane operator increases the current flowing through the electromagnet. What effect will this most likely produce?

Q5. Why is a soft iron core used inside the electromagnet instead of a permanent magnet?

 Data/Logic-Based 

Q6. A scrap yard crane lifted the following objects:

Based on the table, what conclusion can be drawn about materials attracted by electromagnets?

ANSWER KEY WITH EXPLANATION

A1. C. Plastic is a non-magnetic material
 Explanation:  Electromagnets attract magnetic materials such as iron and steel. Plastic does not get magnetised, so it is not attracted.

A2. B. Flow of electric current through the coil
 Explanation:  According to NCERT, electric current flowing through a conductor creates a magnetic field around it. The coil strengthens this effect.
To visualize the direction of this field, students often use the Right-Hand Thumb Rule and Fleming’s Rules, which are handy tricks for exam day.

A3. A. Both A and R are true, and R is the correct explanation of A
 Explanation:  Electromagnets work only when electric current flows through the coil. Switching off the current removes the magnetic field.

A4. The electromagnet will become stronger and can lift heavier metal objects.
While magnets lift things, the same principles allow us to move things - like in electric motors that power your fans. Or, looking at the process in reverse, you can see how power plants generate the electricity we use every day.

A5. Soft iron is used because it becomes magnetised easily and loses magnetism quickly when current is switched off.

A6. Electromagnets attract only magnetic materials like iron and steel.

 Ready to test your knowledge? Download our Class 10 Physics Worksheet for more practice. For a full exam rehearsal, try solving this Unsolved Practice Paper, or check your progress against our Solved Practice Papers.

HOTS EXTENSION QUESTIONS

Q1. A scrap crane is unable to lift a heavy steel beam even though current is flowing through the electromagnet. Suggest two possible ways to increase the lifting power of the crane.

Q2. Predict what might happen if the electromagnet inside the crane used a plastic core instead of a soft iron core. Explain your reasoning.

 Learn More 
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