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What happens to a compass needle when placed near a current-carrying wire?
- a)It aligns with the earth’s magnetic field
- b)It deflects from its north-south position
- c)It starts to spin
- d)It remains unaffected
Correct answer is option 'B'. Can you explain this answer?
Most Upvoted Answer
What happens to a compass needle when placed near a current-carrying w...
When a compass needle is placed near a current-carrying wire, it will experience a magnetic field created by the electric current flowing through the wire. This magnetic field interacts with the magnetic field of the compass, causing the needle to deflect from its usual north-south alignment. The direction of the deflection depends on the direction of the current in the wire and the orientation of the compass.
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What happens to a compass needle when placed near a current-carrying w...
Effect of Current on a Compass Needle
When a compass needle is placed near a current-carrying wire, it experiences a change in its orientation due to the magnetic field created by the electric current. Here's a detailed explanation of why the correct answer is option 'B'.
Magnetic Field Around a Wire
- A current-carrying wire generates a magnetic field around it.
- This magnetic field is circular and its direction can be determined by the right-hand rule: if you point your thumb in the direction of current flow, your curled fingers show the direction of the magnetic field.
Interaction with the Compass Needle
- The compass needle, which is a small magnet itself, aligns with the magnetic field lines.
- When it is placed near the wire, the magnetic field from the wire exerts a force on the needle.
Deflection from North-South Position
- Due to the magnetic field created by the current, the compass needle will deflect from its usual north-south alignment.
- Instead of pointing to the Earth's magnetic north, it will rotate and point in the direction of the magnetic field produced by the wire.
Conclusion
- Therefore, the compass needle does not remain unaffected (option 'D'), nor does it align with the Earth's magnetic field (option 'A') or start to spin (option 'C').
- The correct and observable behavior is that it deflects from its north-south position (option 'B'), clearly demonstrating the influence of an external magnetic field on a magnetic object.
When a compass needle is placed near a current-carrying wire, it experiences a change in its orientation due to the magnetic field created by the electric current. Here's a detailed explanation of why the correct answer is option 'B'.
Magnetic Field Around a Wire
- A current-carrying wire generates a magnetic field around it.
- This magnetic field is circular and its direction can be determined by the right-hand rule: if you point your thumb in the direction of current flow, your curled fingers show the direction of the magnetic field.
Interaction with the Compass Needle
- The compass needle, which is a small magnet itself, aligns with the magnetic field lines.
- When it is placed near the wire, the magnetic field from the wire exerts a force on the needle.
Deflection from North-South Position
- Due to the magnetic field created by the current, the compass needle will deflect from its usual north-south alignment.
- Instead of pointing to the Earth's magnetic north, it will rotate and point in the direction of the magnetic field produced by the wire.
Conclusion
- Therefore, the compass needle does not remain unaffected (option 'D'), nor does it align with the Earth's magnetic field (option 'A') or start to spin (option 'C').
- The correct and observable behavior is that it deflects from its north-south position (option 'B'), clearly demonstrating the influence of an external magnetic field on a magnetic object.
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