(a) Draw a labelled diagram to show the pattern of magnetic field lines produced due to a current carrying straight conductor. Mark on it the direction of current in the conductor and the direction of magnetic field lines. OR (b) Name the device used to magnetise a piece of magnetic material. Draw a labelled diagram to show the arrangement used for the magnetisation of a cylinder made of soft iron.

Q: (a) Draw a labelled diagram to show the pattern of magnetic field lines produced due to a current carrying straight conductor. Mark on it the direction of current in the conductor and the direction of magnetic field lines. OR (b) Name the device used to magnetise a piece of magnetic material. Draw a labelled diagram to show the arrangement used for the magnetisation of a cylinder made of soft iron.

### Option (a) When a direct current flows vertically upwards through a straight conductor, the magnetic field lines produced around it are in the form of concentric circles in a horizontal plane. The direction of these magnetic field lines is given by the **Right-Hand Thumb Rule** (anticlockwise when viewed from above). ```diagram {"xrange": [199.0, 201.0], "yrange": [-255.2, 5.2], "lines": [{"from": [200.0, -20.0], "to": [200.0, -230.0], "label": "Straight Conductor"}, {"from": [200.0, -130.0], "to": [200.0, -70.0], "label": "Current (I) Upward"}], "points": [{"x": 200.0, "y": -150.0, "label": "Magnetic Field Line (Anticlockwise)"}, {"x": 200.0, "y": -150.0, "label": ""}]} ``` --- ### OR ### Option (b) The device used to magnetise a piece of magnetic material is a **solenoid** (which, when carrying current with a magnetic core inside, forms an **electromagnet**). To magnetise a cylinder made of soft iron, it is placed inside a current-carrying solenoid coil. The strong magnetic field produced inside the solenoid magnetises the soft iron core. ```diagram {"xrange": [76.0, 324.0], "yrange": [-180.8, -69.2], "polygons": [{"points": [[100.0, -80.0], [300.0, -80.0], [300.0, -120.0], [100.0, -120.0]]}, {"points": [[170.0, -150.0], [230.0, -150.0], [230.0, -170.0], [170.0, -170.0]]}], "lines": [{"from": [100.0, -100.0], "to": [100.0, -160.0], "label": ""}, {"from": [300.0, -100.0], "to": [300.0, -160.0], "label": ""}], "points": [{"x": 200.0, "y": -100.0, "label": "Soft Iron Cylinder (Core)"}, {"x": 200.0, "y": -160.0, "label": "Battery & Key"}]} ```

Magnetic Effects of Electric Current

Magnetic Field due to a Straight Conductor and Solenoid

Official Answer

Option (a)

When a direct current flows vertically upwards through a straight conductor, the magnetic field lines produced around it are in the form of concentric circles in a horizontal plane. The direction of these magnetic field lines is given by the Right-Hand Thumb Rule (anticlockwise when viewed from above).

OR

Option (b)

The device used to magnetise a piece of magnetic material is a solenoid (which, when carrying current with a magnetic core inside, forms an electromagnet).

To magnetise a cylinder made of soft iron, it is placed inside a current-carrying solenoid coil. The strong magnetic field produced inside the solenoid magnetises the soft iron core.

Concentric circlesRight-Hand Thumb RuleSolenoidSoft iron coreElectromagnetBattery

Marking Scheme

1Option (a): Drawing concentric circles around the straight conductor with correct labels: 1 Mark
2Option (a): Correctly marking the direction of current and the corresponding direction of magnetic field lines: 1 Mark
3OR
4Option (b): Naming the device (Solenoid / Electromagnet): 0.5 Mark
5Option (b): Drawing a neat, labelled diagram showing the soft iron core inside the solenoid connected to a battery: 1.5 Marks

Hint

For (a), use the Right-Hand Thumb Rule to determine the direction of concentric circles. For (b), remember that a solenoid acts as an electromagnet when a soft iron core is inserted inside its coils.

Quick Oral Answer

An electromagnet is a temporary magnet consisting of a core of soft iron placed inside a solenoid. It loses its magnetism as soon as the current in the solenoid is switched off.

Analysis & Explanation

In Option (a), the Right-Hand Thumb Rule states that if you hold a current-carrying straight conductor in your right hand with the thumb pointing in the direction of the current, your wrapped fingers show the direction of the magnetic field lines.

In Option (b), a solenoid is a long coil containing a large number of close turns of insulated copper wire. When current passes through it, it creates a uniform magnetic field inside. Placing a soft iron core inside this uniform field magnetises it by induction, creating an electromagnet.

Common Mistakes

1Forgetting to draw arrows indicating the direction of current and magnetic field lines.
2Drawing intersecting magnetic field lines, which is physically impossible.
3In Option (b), failing to show the battery/power source in the circuit diagram.

Interesting Facts

The unit of magnetic field strength is named the 'oersted' in honor of Hans Christian Oersted, who accidentally discovered electromagnetism in 1820 when a compass needle deflected near a current-carrying wire.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2024?

This question carries 2 marks in the CBSE Class 10 Science 2024 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Magnetic Effects of Electric Current" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Magnetic Field due to a Straight Conductor and Solenoid" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2024 paper?

This is a Very Short Answer question from Section B in the CBSE Class 10 Science 2024 paper.