A wire carrying current i is shaped as shown. Section AB is a quarter circle of radius r. The magnetic field is directed :
(a) At an angle to the plane of the paper
(b) Perpendicular to the plane of the paper and directed in to the paper
(c) Along the bisector of the angle ACB towards AB
(d) Along the bisector of the angle ACB away from AB
The earth’s magnetic field at a given point is This field is to be annulled by magnetic induction at the center of a circular conducting loop of radius 5.0cm. The current required to be flown in the loop is nearly :
(1) 0.2 A
(2) 0.4A
(3) 4A
(4) 40A
A part of a long wire carrying a current i is bent into a circle of radius r as shown in the figure. The net magnetic field at the centre O of the circular loop is
(1)
(2)
(3)
(4)
What is the magnetic field at point O in the figure?
1.
2.
3.
4.
Two thin long parallel wires separated by a distance b are carrying a current i amp each. The magnitude of the force per unit length exerted by one wire on the other is
(1)
(2)
(3)
(4)
In a moving coil galvanometer, the deflection of the coil is related to the electrical current i by the relation
(1)
(2)
(3)
(4)
A moving coil galvanometer has N number of turns in a coil of effective area A, it carries a current I. The magnetic field B is radial. The torque acting on the coil is
(1)
(2)
(3)
(4)
Three long, straight, and parallel wires carrying currents 30A, 10A, and 20A in P, Q, and R respectively are arranged as shown in the figure. The force experienced by 10 cm length of wire Q is
(a) towards the right
(b) towards the left
(c) to the right
(d) to the left
A non-planar loop of conducting wire carrying a current I is placed as shown in the figure. Each of the straight sections of the loop is of length 2a. The magnetic field due to this loop at the point P (a,0,a) points in the direction
(1)
(2)
(3)
(4)
A long straight wire along the z-axis carries a current I in the negative z-direction. The magnetic field vector at a point having coordinates (x, y) in the z = 0 plane is :
1.
2.
3.
4.
A circular coil is in the y-z plane with its centre at the origin. The coil carries a constant current. Assuming the direction of the magnetic field at x = – 25 cm to be positive, which of the following graphs shows the variation of the magnetic field along the x-axis?
1. | 2. | ||
3. | 4. |
Figure shows a square loop ABCD with edge length a. The resistance of the wire ABC is r
and that of ADC is 2r. The value of magnetic field at the centre of the loop assuming
uniform wire is
1.
2.
3.
4.
In the given figure net magnetic field at O will be i
(a) (b)
(c) (d)
In the following figure a wire bent in the form of a regular polygon of n sides is inscribed in a circle of radius a. Net magnetic field at centre will be
(a) (b)
(c) (d)
The unit vectors are as shown below. What will be the magnetic field at O in the following figure?
(a) (b)
(c) (d)
A current I is carried by an elastic circular wire of length L. It is placed in a uniform magnetic field B (out of paper) with its plane perpendicular to B's direction. What will happen to the wire?
\(F ~\)
1. | No force | 2. | A stretching force |
3. | A compressive force | 4. | A torque |
Wires 1 and 2 carrying currents and respectively are inclined at an angle to each other. What is the force on a small element dl of wire 2 at a distance of r from wire 1 (as shown in figure) due to the magnetic field of wire 1
(a) (b)
(c) (d)
A long wire A carries a current of 10 amp. Another long wire B, which is parallel to A and separated by 0.1m from A, carries a current of 5 amp, in the opposite direction to that in A. what is the magnitude and nature of the force experienced per unit length of B
1. repulsive force of
2. attractive force of
3. repulsive force of
4. attractive force of
A, B, and C are parallel conductors of equal length carrying currents I, I, and 2I respectively. Distance between A and B is x. Distance between B and C is also x. is the force exerted by B on A and is the force exerted by C on A choose the correct answer:
1.
2.
3.
4.
There long straight wires A, B and C are carrying current as shown figure. Then the resultant force on B is directed
(1) Towards A
(2) Towards C
(3) Perpendicular to the plane of paper and outward
(4) Perpendicular to the plane of paper and inward
Two long conductors, separated by a distance d carry current and in the same direction. They exert a force F on each other. Now the current in one of them is increased to two times and its direction is reversed. The distance is also increased to . The new value of the force between them is-
1.
2.
3.
4.
Current i is carried in a wire of length L. If the wire is turned into a circular coil, the maximum magnitude of torque in a given magnetic field B will be:
1. 2.
3. 4.
What will happen if two thin, long parallel wires separated by a distance "d" carry current "i" in the same direction?
1. | attract each other with a force per unit length of |
2. | repel each other with a force per unit length of |
3. | attract each other with a force per unit length of |
4. | repel each other with a force per unit length of |
Three long, straight parallel wires carrying current, are arranged as shown in figure. The force experienced by a 25 cm length of wire C is
(1)
(2)
(3) Zero
(4)
An arrangement of three parallel straight wires placed perpendicular to the plane of paper carrying the same current I along the same direction as shown in the figure. Magnitude of force per unit length on the middle wire B is given by:
1.
2.
3.
4.
A long wire carrying a steady current is bent into a circular loop of one turn. The magnetic field at the center of loop is B. It is then bent into a circular coil of n turns. The magnetic field at the centre of this coil of n turns will be
1. nB
2.
3. 2nB
4.
A wire carrying current l has the shape as shown in the adjoining figure. Linear parts of the wire are very long and parallel to X-axis while the semicircular portion of radius R is lying in the Y-Z plane. Magnetic field at point O is :
1.
2.
3.
4.
A proton and an alpha particle both enter a region of uniform magnetic field B, moving at right angles to the field B. If the radius of circular orbits for both the particles is equal and the kinetic energy acquired by proton is 1 MeV, the energy acquired by the alpha particle will be
(1)4 MeV
(2) 0.5 MeV
(3) 1.5 MeV
(4) 1 MeV
Two identical long conducting wires AOB and COD are placed at right angle to each other, with one above other such that O is their common point for the two. The wires carry I1 and I2 currents, respectively. Point P is lying at distance d from 0 along a direction perpendicular to the plane containing the wires. The magnetic field at the point P will be
(1) μo/2πd(I1/I2)
(2)μo/2πd (I1+I2)
(3)μo/2πd(I12-I22)
(4)μo/2πd(I12+I22)1/2
When a proton is released from rest in a room, it starts with an initial acceleration towards west. When it is projected towards north with a speed , it moves with an initial acceleration 3 towards west. The electric and magnetic fields in the room are
(a) mao/e west, 4mao/evo up
(b) mao/e west, 2mao/evo down
(c) mao/e east, 3mao/evo up
(d) mao/e east, 3mao/evo down
A current loop in a magnetic field
(1) experiences a torque whether the field is uniform or non-uniform in all orientations
(2) can be in equilibrium in one orentations.
(3) can be equilibrium in two orientations, both the wquilibriu states are unstable
(4) can be in equilibrium in two orientations, one stable while the other is unstable
An alternating electric field of frequency v, is applied across the dees (radius=R) of a cyclotron that is being used to accelerate protons(mass=m).The operating magnetic field (B) used in the cyclotron and the kinetic energy (K) of the proton beam, produced by it, are given by
(1)B=
(2)B=
(3)B=
(4)B=
A proton carrying 1 MeV kinetic energy is moving in a circular path of radius R in a uniform magnetic field. What should be the energy of an -particle to describe a circle of the same radius in the same field?
1. 2 MeV 2. 1 MeV
3. 0.5 MeV 4. 4 MeV
A current-carrying closed loop in the form of a right-angle isosceles triangle ABC is placed in a uniform magnetic field acting along AB. If the magnetic force on the arm BC is F, the force on the arm AC is:
1. 2.
3. 4.
A uniform electric field and a uniform magnetic field are acting in the same direction in a certain region. If an electron is projected in the region such that its velocity is pointed along the direction of fields, then the electron :
1. speed will decrease
2. speed will increase
3. will turn towards the left of the direction of motion
4. will turn towards right of direction a motion
A square loop, carrying a steady current I, is placed in a horizontal plane near a long straight conductor carrying a steady current at a distance d from the conductor as shown in figure. The loop will experience
(1) a net repulsive force away from the conductor
(2) a net torque acting upward perpendicular to the horizontal plane
(3) a net torque acting downward normal to the horizontal plane
(4) a net attractive force towards the conductor
A beam of cathode rays is subjected to crossed Electric (E) and magnetic fields(B). The fields are adjusted such that the beam is not deflected. The specific charge of the cathode rays is given by:
1.
2.
3.
4.
(where V is the potential difference between cathode and anode)
A thin ring of radius R metre has charge q coulomb uniformly spread on it.The ring rotates about its axis with a constant frequency of f revolution/s.The value of magnetic induction in at the centre of the ring is
(a) (b)
(c) (d)
A current loop consists of two identical semicircular parts each of radius \(R\), one lying in the x-y plane, and the other in the x-z plane. If the current in the loop is \(i\), what will be the resultant magnetic field due to the two semicircular parts at their common centre?
1. | \( \frac{\mu_0 i}{2 \sqrt{2} R} \) | 2. | \( \frac{\mu_0 i}{2 R} \) |
3. | \( \frac{\mu_0 i}{4 R} \) | 4. | \( \frac{\mu_0 i}{\sqrt{2} R}\) |
A particle having a mass of carries a charge of The particle is given an initial horizontal velocity of in the presence of electric field and magnetic field . To keep the particle moving in a horizontal direction, it is necessary that
(1) should be perpendicular to the direction of velocity and should be along the direction of velocity.
(2) Both and should be along the direction of velocity.
(3) Both and are mutually perpendicular and perpendicular to the direction of velocity.
(4) should be along the direction of velocity and should be perpendicular to the direction of velocity.
Which one of the following pairs of statements are possible?
1. (1) and (3) 2. (3) and (4)
3. (2) and (3) 4. (2) and (4)
Under the influence of a uniform magnetic field, a charged particle moves with constant speed v in a circle of radius R. The time period of rotation of the particle -
1. depends on v and not on R
2. depends on R and not on v
3. is independent of both v and R
4. depends on both v and R
The magnetic force acting on a charged particle of charge in a magnetic field of 2T acting in y-direction, when the particle velocity is is.
1. 8 N in -z-direction
2. 4 N in z-direction
3. 8 N in y-direction
4. 4 N in y-direction
A particle mass m, charge Q, and kinetic energy T enter a transverse uniform magnetic field of induction . After 3sec the kinetic energy of the particle will be :
1. 3T
2. 2T
3. T
4. 4T
A beam of electrons is moving with constant velocity in a region having electric and magnetic fields of strength and 0.5 T at right angles to the direction of motion of the electrons. What is the velocity of the electrons
1. 20 2. 40
3. 8 4. 5.5
Order of q/m ratio of proton, -particle and electron is
(a) (b)
(c) (d) None of these