Exams › JEE Main › Physics
A loop of flexible wire of irregular shape carrying current is placed in an external magnetic field. Identify the effect of the field on the wire. (1) Loop assumes circular shape with its plane normal to the field. (2) Loop assumes circular shape with its plane parallel to the field. (3) Wire gets stretched to become straight. (4) Shape of the loop remains unchanged.
- (1) Loop assumes circular shape with its plane normal to the field.
- (2) Loop assumes circular shape with its plane parallel to the field.
- (3) Wire gets stretched to become straight.
- (4) Shape of the loop remains unchanged.
Correct answer: (1) Loop assumes circular shape with its plane normal to the field.
Solution
When a current-carrying loop is placed in a magnetic field, it experiences a torque that tends to align the plane of the loop perpendicular to the magnetic field lines, resulting in a circular shape with its plane normal to the field.
Related JEE Main Physics questions
- A tightly wound solenoid has 2000 turns and a cross-sectional area of $1.5 \times 10^{-4}\,\text{m}^2$. It carries a current of 2.0 A and is hung at its center with its axis perpendicular to its length so that it can rotate in a horizontal plane. If it is placed in a uniform magnetic field of strength $5 \times 10^{-2}\,\text{T}$, and the field makes an angle of $30^\circ$ with the solenoid axis, what torque acts on the solenoid?
- A cyclotron with dee radius $R$ is used to speed up protons of mass $m$. An alternating electric field of frequency $\nu$ is applied across the dees. For the cyclotron to operate, the magnetic field $B$ and the kinetic energy $K$ of the emerging proton beam are related by:
- A long, straight conductor of radius $a$ carries a constant current $I$ that is spread uniformly over its cross-sectional area. What is the ratio of the magnetic field at a distance $a/2$ from the axis to the magnetic field at a distance $2a$ from the axis?
- Two tangent galvanometers, A and B, have coil radii of 8 cm and 16 cm respectively, and each has a resistance of 8 $\Omega$. They are joined in parallel. When the applied voltages are 4 V and 6 V respectively, the corresponding deflections in A and B are 30$^\circ$ and 60$^\circ$. If galvanometer A has 2 turns, the number of turns in B is
- A charge of $2\,\mu\text{C}$ revolves with a frequency of $6.25\times 10^{12}\,\text{Hz}$ and creates a magnetic field of $6.28\,\text{T}$ at a point on the circle. What is the radius of the circular path?
- An electron beam travels through a region where uniform electric and magnetic fields act mutually perpendicular to each other, and both are also perpendicular to the direction of motion of the electrons. If the electric field strength is $20\,\text{V m}^{-1}$ and the magnetic field strength is $0.5\,\text{T}$, the speed of the electrons must be
⚔️ Practice JEE Main Physics free + battle 1v1 →