When a compass is placed near the loop of a current-carrying circular coil, what does the compass needle’s alignment reveal about the field lines produced by the coil?
The compass needle aligns tangentially to the circular field lines at that point, indicating the direction of the magnetic field.
A current-carrying circular loop produces a magnetic field. Near each segment of the wire the field lines are concentric circles around the wire, which become nearly straight and parallel near the centre of the loop.
A compass needle is a small magnet that is free to rotate, so it always comes to rest along the magnetic field at its location. The magnetic field at any point acts along the tangent to the field line passing through that point.
So the needle aligns tangentially to the circular field line where it is placed, and its north pole points in the direction of the field there. Moving the compass around the wire traces out these circular lines.
The needle never settles at right angles to the field, because the field exerts a torque that turns it into line with the field. For a steady current the field is steady, so the needle does not move randomly, and it does not always point towards the centre of the coil, since the field lines are not radial.
Hence, The compass needle aligns tangentially to the circular field lines at that point, indicating the direction of the magnetic field.
Similar Questions
What does the presence of parallel straight magnetic field lines inside a solenoid indicate?
Two parallel, straight wires carry equal currents in opposite directions. If the magnetic fields produced by the two wires are equal in magnitude and opposite in direction at a point, what is the resultant magnetic field at that point?
What happens to the magnetic field at the center of a circular coil when the number of turns is increased to n, assuming the current remains the same?
A student observes the pattern formed by iron filings around a straight current-carrying conductor. The arrangement of filings demonstrates a property of magnetic fields. Which feature is illustrated by their pattern?
A student modifies the experiment by replacing the copper wire with a plastic thread between points X and Y, keeping all other conditions unchanged. What will be the expected observation regarding the compass needle and why?
Important Questions from Magnetism
- The magnetic field around a straight current-carrying conductor:
Magnetic field is a quantity that has___________________ .
- The right-hand thumb rule is used to find which of the following?
- How are the magnetic field lines arranged inside a current-carrying solenoid?
- What does it mean when magnetic field lines are drawn closer together in a diagram?
