A circular coil of radius 2.0cm has 500 turns and carries a current of 1.0A. Its axis makes an angle of 30° with the uniform magnetic field of magnitude 0.40 T that exists in the space. Find the torque acting on the coil.
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Magnetic Field question types
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91
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6
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2 Marks Questions
14 Q→023 Marks Question
19 Q→031 Marks Question
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1 Q→05M.C.Q (1 Marks)
20 Q→065 Marks Questions
32 Q→Sample Questions
Magnetic Field questions
One sample from each question group in this chapter. Select any group above to see the full set with answer keys.
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Verify that the units weber and volt-second are the same.
A wire, carrying a current i, is kept in the x−y plane along the curve $\text{y}=\text{A}\sin\Big(\frac{2\pi}{\lambda}\text{x}\Big).$ A magnetic field B exists in the z direction. Find the magnitude of the magnetic force on the portion of the wire between $\text{x}=0$ and $\text{x}=\lambda.$
View full solution →The torque on a current loop is zero if the angle between the positive normal and the magnetic field is either $\theta=0^\circ$ or $\theta=180^\circ$ In which of the two orientations, the equilibrium is stable?
View full solution →A semicircular wire of radius 5.0cm carries a current of 5.0A. A magnetic field B of magnitude 0.50T exists along the perpendicular to the plane of the wire. Find the magnitude of the magnetic force acting on the wire.
A current loop of arbitrary shape lies in a uniform magnetic field B. Show that the net magnetic force acting on the loop is zero.
A metal wire PQ of mass 10g lies at rest on two horizontal metal rails separated by 4.90cm A vertically-downward magnetic field of magnitude 0.800T exists in the space. The resistance of the circuit is slowly decreased and it is found that when the resistance goes below 20.0Ω, the wire PQ starts sliding on the rails. Find the coefficient of friction.
Consider a non-conducting ring of radius r and mass m that has a total charge q distributed uniformly on it. The ring is rotated about its axis with an angular speed $\omega.$
View full solution →- Find the equivalent electric current in the ring.
- Find the magnetic moment $\mu$ of the ring.
- Show that $\mu=\frac{\text{q}}{2\text{m}}\text{l}$ where l is the angular momentum of the ring about its axis of rotation.
A square coil of edge l and with n turns carries a current i. It is kept on a smooth horizontal plate. A uniform magnetic field B exists parallel to an edge. The total mass of the coil is M. What should be the minimum value of B for which the coil will start tipping over?
A magnetic field of strength 1.0T is produced by a strong electromagnet in a cylindrical region of radius 4.0cm, as shown in the figure. A wire, carrying a current of 2.0A, is placed perpendicular to and intersecting the axis of the cylindrical region. Find the magnitude of the force acting on the wire.
Will a current loop placed in a magnetic field always experience a zero force?
The free electrons in a conducting wire are in constant thermal motion. If such a wire, carrying no current, is placed in a magnetic field, is there a magnetic force on each free electron? On the wire?
Can a charged particle be accelerated by a magnetic field? Can its speed be increased?
Is it possible for a current loop to stay without rotating in a uniform magnetic field? If yes, what should be the orientation of the loop?
Suppose a charged particle moves with a velocity v near a wire carrying an electric current. A magnetic force, therefore, acts on it. If the same particle is seen from a frame moving with velocity v in the same direction, the charge will be found at rest. Will the magnetic force become zero in this frame? Will the magnetic field become zero in this frame?
Shows a rod PQ of length 20.0cm and mass 200g suspended through a fixed point O by two threads of lengths 20.0cm each. A magnetic field of strength 0.500T exists in the vicinity of the wire PQ, as shown in the figure. The wires connecting PQ with the battery are loose and exert no force on PQ.
- Find the tension in the threads when the switch S is open.
- A current of 2.0A is established when the switch S is closed. Find the tension in the threads now.
Let $\overrightarrow{\text{E}}$ and $\overrightarrow{\text{B}}$ denote electric and magnetic fields in a frame S and $\overrightarrow{\text{E}}$ and $\overrightarrow{\text{B}}$ in another frame S moving with respect to S at a velocity $\overrightarrow{\text{v}}.$ Two of the following equations are wrong. Identify them.
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$\text{B}_\text{y},=\text{B}_\text{y}+\frac{\text{vE}_\text{z}}{\text{c}^2}$
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$\text{E}_\text{y},=\text{E}_\text{y}+\frac{\text{vB}_\text{z}}{\text{c}^2}$
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$\text{B}'_\text{y}=\text{B}_\text{y}+\text{v}\text{E}_\text{z}$
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$\text{E}'_\text{y}=\text{E}_\text{y}+\text{vB}_\text{z}$
A charged particle goes undeflected in a region containing an electric and a magnetic field. It is possible that
View full solution →- $\overrightarrow{\text{E}}||\overrightarrow{\text{B}},\ \overrightarrow{\text{v}}||\overrightarrow{\text{E}}$
- $\overrightarrow{\text{E}}$ is not parallel to $\overrightarrow{\text{B}}$
- $\overrightarrow{\text{v}}||\overrightarrow{\text{B}}$ but $\overrightarrow{\text{E}}$ is not parallel to $\overrightarrow{\text{B}}$
- $\overrightarrow{\text{E}}||\overrightarrow{\text{B}}$ but $\overrightarrow{\text{v}}$ is not parallel to $\overrightarrow{\text{E}}$
An electric current i enters and leaves a uniform circular wire of radius a through diametrically opposite points. A charged particle q moving along the axis of the circular wire passes through its centre at speed v. The magnetic force acting on the particle when it passes through the centre has a magnitude:
View full solution →- $\text{qv}\frac{\mu_0\text{i}}{2\text{a}}$
- $\text{qv}\frac{\mu_0\text{i}}{2\pi\text{a}}$
- $\text{qv}\frac{\mu_0\text{i}}{\text{a}}$
- $\text{Zero}$
A circular loop of area 1cm2, carrying a current of 10A, is placed in a magnetic field of 0.1T perpendicular to the plane of the loop. The torque on the loop due to the magnetic field is:
- Zero
- 104N-m
- 102N-m
- 1N-m
Which of the following particles will describe the smallest circle when projected with the same velocity perpendicular to a magnetic field?
- Electron
- Proton
- He+
- Li+
A particle of mass m and positive charge q, moving with a uniform velocity v, enters a magnetic field B, as shown,
- Find the radius of the circular arc it describes in the magnetic field.
- Find the angle subtended by the arc at the centre.
- How long does the particle stay inside the magnetic field?
- Solve the three parts of the above problem if the charge q on the particle is negative.
An electron is projected horizontally with a kinetic energy of 10keV. A magnetic field of strength 1.0 × 10-7T exists in the vertically upward direction.
- Will the electron deflect towards the right or left of its motion?
- Calculate the sideways deflection of the electron while travelling through 1m. Make appropriate approximations.
Two particles, each with mass m are placed at a separation d in a uniform magnetic field B, as shown in the figure. They have opposite charges of equal magnitude q. At time t = 0, the particles are projected towards each other, each with a speed v. Suppose the Coulomb force between the charges is switched off.
View full solution →- Find the maximum value vm of the projection speed, so that the two particles do not collide.
- What would be the minimum and maximum separation between the particles if $\text{v}=\text{v}_{\text{m}}\sqrt{2}?$
- At what instant will a collision occur between the particles if v = 2vm?
- Suppose v = 2vm and the collision between the particles is completely inelastic. Describe the motion after the collision.
Shows a convex lens of focal length 12cm lying in a uniform magnetic field B of magnitude 1.2T parallel to its principal axis. A particle with charge 2.0 × 10-3C and mass 2.0 × 10-5 kg is projected perpendicular to the plane of the diagram with a speed of 4.8 ms-1. The particle moves along a circle with its centre on the principal axis at a distance of 18cm from the lens. Show that the image of the particle moves along a circle and find the radius of that circle.
Consider a non-conducting plate of radius r and mass m that has a charge q distributed uniformly over it. The plate is rotated about its axis with an angular speed $\omega.$ Show that the magnetic moment $\mu$ and the angular momentum of the plate are related as $\mu=\frac{\text{q}}{2\text{m}}\text{l}.$
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