Physics-
General
Easy
Question
A rectangular coil PQ has 2n turns, an area 2a and carries a current 2I, (refer figure). The plane of the coil is at 60° to a horizontal uniform magnetic field of flux density B. The torque on the coil due to magnetic force is
- B n a I sin60°
- 8BnaI cos60°
- 4naI Bsin60°
- none
The correct answer is: 8BnaI cos60°
Related Questions to study
physics-
A thin non conducting disc of radius R is rotating clockwise (see figure) with an angular velocity w about its central axis, which is perpendicular to its plane. Both its surfaces carry +ve charges of uniform surface density. Half the disc is in a region of a uniform, unidirectional magnetic field B parallel to the plane of the disc, as shown. Then,
A thin non conducting disc of radius R is rotating clockwise (see figure) with an angular velocity w about its central axis, which is perpendicular to its plane. Both its surfaces carry +ve charges of uniform surface density. Half the disc is in a region of a uniform, unidirectional magnetic field B parallel to the plane of the disc, as shown. Then,
physics-General
physics-
In the figure shown a coil of single turn is wound on a sphere of radius R and mass m. The plane of the coil is parallel to the plane and lies in the equatorial plane of the sphere. Current in the coil is i. The value of B if the sphere is in equilibrium is
In the figure shown a coil of single turn is wound on a sphere of radius R and mass m. The plane of the coil is parallel to the plane and lies in the equatorial plane of the sphere. Current in the coil is i. The value of B if the sphere is in equilibrium is
physics-General
physics-
A conducting ring of mass 2 kg and radius 0.5 m is placed on a smooth horizontal plane. The ring carries a current i = 4A. A horizontal magnetic field B = 10T is switched on at time t = 0 as shown in figure. The initial angular acceleration of the ring will be
A conducting ring of mass 2 kg and radius 0.5 m is placed on a smooth horizontal plane. The ring carries a current i = 4A. A horizontal magnetic field B = 10T is switched on at time t = 0 as shown in figure. The initial angular acceleration of the ring will be
physics-General
physics-
In given figure, X and Y are two long straight parallel conductors each carrying a current of 2 A. The force on each conductor is F newtons. When the current in each is changed to 1 A and reversed in direction, the force on each is now
In given figure, X and Y are two long straight parallel conductors each carrying a current of 2 A. The force on each conductor is F newtons. When the current in each is changed to 1 A and reversed in direction, the force on each is now
physics-General
physics-
A square loop ABCD, carrying a current i, is placed near and coplanar with a long straight conductor XY carrying a current I, the net force on the loop will be
A square loop ABCD, carrying a current i, is placed near and coplanar with a long straight conductor XY carrying a current I, the net force on the loop will be
physics-General
physics-
In the figure shown a current I1 is established in the long straight wire AB. Another wire CD carrying current I2 is placed in the plane of the paper. The line joining the ends of this wire is perpendicular to the wire AB. The force on the wire CD is:
In the figure shown a current I1 is established in the long straight wire AB. Another wire CD carrying current I2 is placed in the plane of the paper. The line joining the ends of this wire is perpendicular to the wire AB. The force on the wire CD is:
physics-General
physics-
A circular current loop of radius a is placed in a radial field B as shown. The net force acting on the loop is
A circular current loop of radius a is placed in a radial field B as shown. The net force acting on the loop is
physics-General
Physics-
A semi circular current carrying wire having radius R is placed in x-y plane with its centre at origin ‘O’. There is non-uniform magnetic field 
(here Bo is +ve constant) is existing in the region. The magnetic force acting on semi circular wire will be along
A semi circular current carrying wire having radius R is placed in x-y plane with its centre at origin ‘O’. There is non-uniform magnetic field (here Bo is +ve constant) is existing in the region. The magnetic force acting on semi circular wire will be along
Physics-General
physics-
A conducting wire bent in the form of a parabola y2 = 2x carries a current i = 2 A as shown in figure. This wire is placed in a uniform magnetic field 
Tesla. The magnetic force on the wire is (in newton)
A conducting wire bent in the form of a parabola y2 = 2x carries a current i = 2 A as shown in figure. This wire is placed in a uniform magnetic field Tesla. The magnetic force on the wire is (in newton)
physics-General
physics-
A straight rod of mass m and length L is suspended from the identical spring as shown in the figure. The spring stretched by a distance of x0 due to the weight of the wire. The circuit has total resistance RW. When the magnetic field perpendicular to the plane of the paper is switched on, springs are observed to extend further by the same distance. The magnetic field strength is
A straight rod of mass m and length L is suspended from the identical spring as shown in the figure. The spring stretched by a distance of x0 due to the weight of the wire. The circuit has total resistance RW. When the magnetic field perpendicular to the plane of the paper is switched on, springs are observed to extend further by the same distance. The magnetic field strength is
physics-General
physics-
A charged particle enters a uniform magnetic field perpendicular to its initial direction travelling in air. The path of the particle is seen to follow the path in figure. Which of statements 1–3 is/are correct? [1] The magnetic field strength may have been increased while the particle was travelling in air [2] The particle lost energy by ionising the air [3] The particle lost charge by ionising the air
A charged particle enters a uniform magnetic field perpendicular to its initial direction travelling in air. The path of the particle is seen to follow the path in figure. Which of statements 1–3 is/are correct? [1] The magnetic field strength may have been increased while the particle was travelling in air [2] The particle lost energy by ionising the air [3] The particle lost charge by ionising the air
physics-General
physics-
A particle moving with velocity v having specific charge (q/m) enters a region of magnetic field B having width 
at angle 53° to the boundary of magnetic field. Find the angle 
in the diagram.
A particle moving with velocity v having specific charge (q/m) enters a region of magnetic field B having width at angle 53° to the boundary of magnetic field. Find the angle in the diagram.
physics-General
physics-
A block of mass m & charge q is released on a long smooth inclined plane magnetic field B is constant, uniform, horizontal and parallel to surface as shown. Find the time from start when block loses contact with the surface.
A block of mass m & charge q is released on a long smooth inclined plane magnetic field B is constant, uniform, horizontal and parallel to surface as shown. Find the time from start when block loses contact with the surface.
physics-General
physics-
A particle having charge q enters a region of uniform magnetic field 
(directed inwards) and is deflected a distance x after travelling a distance y. The magnitude of the momentum of the particle is:
A particle having charge q enters a region of uniform magnetic field (directed inwards) and is deflected a distance x after travelling a distance y. The magnitude of the momentum of the particle is:
physics-General
physics-
The direction of magnetic force on the electron as shown in the diagram is along
The direction of magnetic force on the electron as shown in the diagram is along
physics-General
