A positively charged particle projected towards east is deflected towards north by a magnetic field. The field may be:
- ✓Towards west.
- BTowards south.
- CUpward.
- DDownward.
Answer: A.
View full solution →Question types
Magnetic Field question types
91 questions across 6 question groups — pick any mix to generate a Physics paper with step-by-step answer keys.
91
Questions
6
Question groups
5
Question types
01
M.C.Q (1 Marks)
20 Q→021 Marks Question
5 Q→032 Marks Questions
14 Q→043 Marks Question
19 Q→055 Marks Questions
32 Q→06Case study (4 Marks)
1 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.
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.
- $\text{B}_\text{y},=\text{B}_\text{y}+\frac{\text{vE}_\text{z}}{\text{c}^2}$
- $\text{E}_\text{y},=\text{E}_\text{y}+\frac{\text{vB}_\text{z}}{\text{c}^2}$
- $\text{B}'_\text{y}=\text{B}_\text{y}+\text{v}\text{E}_\text{z}$
- $\text{E}'_\text{y}=\text{E}_\text{y}+\text{vB}_\text{z}$
- Aonly $A$
- B$A$ and $B$
- ✓$B$ and $C$
- DNone of these
Answer: C.
View full solution →A charged particle goes undeflected in a region containing an electric and a magnetic field. It is possible that
- $\overrightarrow{\text{E}}||\overrightarrow{\text{B}},\ \overrightarrow{\text{v}}||\overrightarrow{\text{E}}$
- $\overrightarrow{\text{E}}$ 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 $\overrightarrow{\text{E}}$
- ✓$A$ and $B$
- Bonly $B$
- C$A$ and $D$
- DNone of these
Answer: A.
View full solution →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:
- A$\text{qv}\frac{\mu_0\text{i}}{2\text{a}}$
- B$\text{qv}\frac{\mu_0\text{i}}{2\pi\text{a}}$
- C$\text{qv}\frac{\mu_0\text{i}}{\text{a}}$
- ✓$\text{Zero}$
Answer: D.
View full solution →A circular loop of area $1 \mathrm{~cm}^2$, carrying a current of $10 A$ , is placed in a magnetic field of $0.1 T$ perpendicular to the plane of the loop. The torque on the loop due to the magnetic field is:
- ✓Zero
- B$10^4 \mathrm{~N}-\mathrm{m}$
- C$10^2 \mathrm{~N}-\mathrm{m}$
- D$1 \mathrm{~N}-\mathrm{m}$
Answer: A.
View full solution →Will a current loop placed in a magnetic field always experience a zero force?
Can a charged particle be accelerated by a magnetic field? Can its speed be increased?
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?
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?
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?
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.
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 →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.
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 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.
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?
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 particle moves in a circle of diameter 1.0cm under the action of a magnetic field of 0.40T. An electric field of $200 Vm^{-1}$ makes the path straight. Find the charge/ mass ratio of the particle.
View full solution →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.
Doubly-ionised helium ions are projected with a speed of $10km/s^{-1}$ in a direction perpendicular to a uniform magnetic field of magnitude 1.0T. Find
View full solution →- The force acting on an ion.
- The radius of the circle in which it circulates.
- The time taken by an ion to complete the circle.
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 $v_m$ 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 $v = 2v_m$?
- Suppose $v = 2v_m$ and the collision between the particles is completely inelastic. Describe the motion after the collision.
An electron is projected horizontally with a kinetic energy of $10keV$. A magnetic field of strength $1.0 \times 10^{-7}T$ exists in the vertically upward direction.
View full solution →- 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.
A magnetic field of $(4.0\times10^{-3}\vec{\text{k}})$ T exerts a force of $(4.0\vec{\text{i}}+3.0\vec{\text{j}})\times10^{-10}$ N on a particle with a charge of $1.0\times10^{-9}\text{C}$ and going in the x−y plane. Find the velocity of the particle.
View full solution →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 $2.0 \times 10^{-3}C$ and mass $2.0 \times 10^{-5} kg$ 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.
View full solution →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.
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