The magnetic field lines inside a current-carrying solenoid are concentric circles.
Important Questions on Magnetic Effects of Electric Current
A copper wire is connected to the terminals of a charged battery. The wire is now kept between the poles of a strong horseshoe magnet in such a way that the force experienced by the wire is maximum.
On the basis of the above information, answer the following:
Which of the following rules will give the direction of the force exerted on the wire?
On the basis of the above information, answer the following:
If the connections to the positive and negative terminals are interchanged and the polarity of the horseshoe magnet is also reversed, how will the direction of the force exerted change?
In the following table, Column I give the unknown and Column II gives the rules to find the unknown. Match the items in Column I to those in Column II.
| Column I | Column II |
| (a) Direction of magnetic field at a point due to a current-carrying conductor. |
(p) Fleming's left-hand rule |
| (b) Direction of force experienced by a current-carrying conductor placed in a magnetic field | (q) Clock-face rule |
| (c) Polarity of a current-carrying solenoid | (r) Fleming's right-hand rule |
| (s) Maxwell's right-hand thumb rule |
A student performs an experiment to study the magnetic effect of current around a current-carrying straight conductor. He reports that
(i) the direction of deflection of the North Pole of a compass needle kept at a given point near the conductor remains unaffected even when the terminals of the battery sending current in the wire are interchanged.
(ii) For a given battery, the degree of deflection of the North Pole of the compass decreases when it is kept at a point farther away from the conductor.
Which of the two observations is correct and why?
A current-carrying conductor is placed perpendicular to the magnetic field of a horseshoe magnet. The conductor is displaced upwards. State what will happen to the displacement of the conductor when
(a) the current in the conductor is increased.
A current-carrying conductor is placed perpendicular to the magnetic field of a horseshoe magnet. The conductor is displaced upwards. State what will happen to the displacement of the conductor when
(b) The horseshoe magnet is replaced by a stronger magnet.
