Deformation of Flexible Current Loop in Magnetic Field – Rankers Physics

Force Acting on Current Carrying Conductor: Practice Problem & Solution

Assertion (A): If a flexible loop (irregular shape) carrying current is located in an external uniform magnetic field then it may be changed to circular shape. Reason (R): A current carrying loop in uniform magnetic field has zero net force.  
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Force Acting on Current Carrying Conductor. Understanding the underlying formula is key to arriving at the correct answer below:

Assertion (A) is true: A current loop in a magnetic field tends to maximize its enclosed area to minimize its magnetic potential energy \(-\vec{M} \cdot \vec{B}\). A circle provides the maximum area for a given perimeter.

Reason (R) is true: The net force on a closed loop in a uniform magnetic field is zero. (R) does not explain (A); the shape change is due to torque and area maximization, not the zero net force. Both are true, but (R) is not the explanation for (A).

Leave a Reply

Your email address will not be published. Required fields are marked *

Similar Practice Questions

Explore conceptually related problems to test your knowledge.

1. Assertion (A): Work done by magnetic force on any moving charge is zero. Reason (R): Magnetic force is perpendicular to velocity.  
2. In crossed electric and magnetic field, the velocity of charged particle which passes undeflected through the region may be (where \(E\) is electric field and \(B\) is magnetic field)
3. 5. A closely wound solenoid of 2000 turns and area of cross section $1.5 \times 10^{-4}\text{ m}^2$ carries a current of $2.0\text{ A}$. It is suspended through its centre and perpendicular to its length, allowing it to turn in a horizontal plane in a uniform magnetic field $5 \times 10^{-2}\text{ tesla}$ making an angle of $30^\circ$ with the axis of the solenoid. The torque on the solenoid will be (2010 Mains)
4. Assertion (A): A charged particle is moving in a circle with constant speed in uniform magnetic field. If we increase the speed of particle to twice, its acceleration will become four times. Reason (R): A charge particle in circular path with constant speed in magnetic field, acceleration is given by centripetal acceleration. If speed is doubled centripetal acceleration will become four times.  
5. Given below are two statements Statement I : Biot-Savart's law gives us the expression for the magnetic field strength of an infinitesimal current element ($I d \vec{l}$) of the current carrying conductor only. Statement II : Biot-Savart's law is analogous to Coulomb's inverse square law of charge $q$, with the former being related to the field produced by a scalar source, $Id \vec{l}$, while the latter being produced by a vector source, $q$. In light of above statements choose the most appropriate answer from the options given below