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MCQOPTIONS
This section includes 12583 Mcqs, each offering curated multiple-choice questions to sharpen your Joint Entrance Exam - Main (JEE Main) knowledge and support exam preparation. Choose a topic below to get started.
| 4901. |
The radius of curvature of the path of a charged particle moving in a static uniform magnetic field is [Roorkee 1999] |
| A. | Directly proportional to the magnitude of the charge on the particle |
| B. | Directly proportional to the magnitude of the linear momentum of the particle |
| C. | Directly proportional to the kinetic energy of the particle |
| D. | Inversely proportional to the magnitude of the magnetic field |
| Answer» C. Directly proportional to the kinetic energy of the particle | |
| 4902. |
One proton beam enters a magnetic field of \[{{10}^{-4}}\]T normally, Specific charge = \[{{10}^{11}}\,C/kg.\] velocity = \[{{10}^{7}}\,m/s\]. What is the radius of the circle described by it [DCE 1999] |
| A. | 0.1 m |
| B. | 1 m |
| C. | 10 m |
| D. | None of these |
| Answer» C. 10 m | |
| 4903. |
In a cyclotron, the angular frequency of a charged particle is independent of [CPMT 1999] |
| A. | Mass |
| B. | Speed |
| C. | Charge |
| D. | Magnetic field |
| Answer» C. Charge | |
| 4904. |
If an electron is going in the direction of magnetic field \[\overrightarrow{B}\] with the velocity of \[\overrightarrow{v\,}\] then the force on electron is [RPMT 1999] |
| A. | Zero |
| B. | \[e\,(\overrightarrow{v\,}\cdot \overrightarrow{B})\] |
| C. | \[e\,(\overrightarrow{v\,}\times \overrightarrow{B})\] |
| D. | None of these |
| Answer» B. \[e\,(\overrightarrow{v\,}\cdot \overrightarrow{B})\] | |
| 4905. |
A particle is moving in a uniform magnetic field, then [BHU 1998] |
| A. | Its momentum changes but total energy remains the same |
| B. | Both momentum and total energy remain the same |
| C. | Both will change |
| D. | Total energy changes but momentum remains the same |
| Answer» B. Both momentum and total energy remain the same | |
| 4906. |
A particle moving in a magnetic field increases its velocity, then its radius of the circle [BHU 1998] |
| A. | Decreases |
| B. | Increases |
| C. | Remains the same |
| D. | Becomes half |
| Answer» C. Remains the same | |
| 4907. |
A positively charged particle moving due east enters a region of uniform magnetic field directed vertically upwards. The particle will [CBSE PMT 1997] |
| A. | Get deflected vertically upwards |
| B. | Move in a circular orbit with its speed increased |
| C. | Move in a circular orbit with its speed unchanged |
| D. | Continue to move due east |
| Answer» D. Continue to move due east | |
| 4908. |
An electron and a proton with equal momentum enter perpendicularly into a uniform magnetic field, then [BHU 1997; AIEEE 2002; MH CET (Med.) 2000] |
| A. | The path of proton shall be more curved than that of electron |
| B. | The path of proton shall be less curved than that of electron |
| C. | Both are equally curved |
| D. | Path of both will be straight line |
| Answer» D. Path of both will be straight line | |
| 4909. |
A charge moving with velocity v in X-direction is subjected to a field of magnetic induction in the negative X-direction. As a result, the charge will [CBSE PMT1993] |
| A. | Remain unaffected |
| B. | Start moving in a circular path Y-Z plane |
| C. | Retard along X-axis |
| D. | Move along a helical path around X-axis |
| Answer» B. Start moving in a circular path Y-Z plane | |
| 4910. |
An electron has mass \[9\times {{10}^{-31}}\,kg\] and charge \[1.6\times {{10}^{-19}}C\] is moving with a velocity of \[{{10}^{6}}\,m/s\], enters a region where magnetic field exists. If it describes a circle of radius 0.10 m, the intensity of magnetic field must be [NCERT 1982; CPMT 1989; DCE 2005] |
| A. | \[1.8\times {{10}^{-4}}\,T\] |
| B. | \[5.6\times {{10}^{-5}}\,T\] |
| C. | \[14.4\times {{10}^{-5}}\,T\] |
| D. | \[1.3\times {{10}^{-6}}\,T\] |
| Answer» C. \[14.4\times {{10}^{-5}}\,T\] | |
| 4911. |
An electron enters a region where magnetic and electric (E) fields are mutually perpendicular to one another, then [CBSE PMT1993] |
| A. | It will always move in the direction of B |
| B. | It will always move in the direction of E |
| C. | It always possess circular motion |
| D. | It can go undeflected also |
| Answer» E. | |
| 4912. |
A proton of energy 200 MeV enters the magnetic field of 5 T. If direction of field is from south to north and motion is upward, the force acting on it will be [RPET 1997] |
| A. | Zero |
| B. | \[1.6\times {{10}^{-10}}N\] |
| C. | \[3.2\times {{10}^{-8}}N\] |
| D. | \[1.6\times {{10}^{-6}}N\] |
| Answer» C. \[3.2\times {{10}^{-8}}N\] | |
| 4913. |
A charge moves in a circle perpendicular to a magnetic field. The time period of revolution is independent of [RPET 1997; AIEEE 2002] |
| A. | Magnetic field |
| B. | Charge |
| C. | Mass of the particle |
| D. | Velocity of the particle |
| Answer» E. | |
| 4914. |
When a magnetic field is applied in a direction perpendicular to the direction of cathode rays, then their [EAMCET 1994; BHU 2005] |
| A. | Energy decreases |
| B. | Energy increases |
| C. | Momentum increases |
| D. | Momentum and energy remain unchanged |
| Answer» E. | |
| 4915. |
A moving charge will gain energy due to the application of [CPMT 1999] |
| A. | Electric field |
| B. | Magnetic field |
| C. | Both of these |
| D. | None of these |
| Answer» B. Magnetic field | |
| 4916. |
An electron is moving along positive x-axis. To get it moving on an anticlockwise circular path in x-y plane, a magnetic filed is applied [MP PMT 1999] |
| A. | Along positive y-axis |
| B. | Along positive z-axis |
| C. | Along negative y-axis |
| D. | Along negative z-axis |
| Answer» C. Along negative y-axis | |
| 4917. |
A charged particle moves in a uniform magnetic field. The velocity of the particle at some instant makes an acute angle with the magnetic field. The path of the particle will be [MP PMT 1999] |
| A. | A straight line |
| B. | A circle |
| C. | A helix with uniform pitch |
| D. | A helix with non-uniform pitch |
| Answer» D. A helix with non-uniform pitch | |
| 4918. |
An electron and a proton enter a magnetic field perpendicularly. Both have same kinetic energy. Which of the following is true [MP PET 1999] |
| A. | Trajectory of electron is less curved |
| B. | Trajectory of proton is less curved |
| C. | Both trajectories are equally curved |
| D. | Both move on straight-line path |
| Answer» C. Both trajectories are equally curved | |
| 4919. |
A charged particle enters a magnetic field H with its initial velocity making an angle of \[45{}^\circ \] with H. The path of the particle will be [MP PET 1999; AIIMS 1999; BHU 1999] |
| A. | A straight line |
| B. | A circle |
| C. | An ellipse |
| D. | A helix |
| Answer» E. | |
| 4920. |
The radius of curvature of the path of the charged particle in a uniform magnetic field is directly proportional to [MNR 1995; UPSEAT 1999, 2000] |
| A. | The charge on the particle |
| B. | The momentum of the particle |
| C. | The energy of the particle |
| D. | The intensity of the field |
| Answer» C. The energy of the particle | |
| 4921. |
A charged particle is moving with velocity v in a magnetic field of induction B. The force on the particle will be maximum when [MP PMT/PET 1998] |
| A. | v and B are in the same direction |
| B. | v and B are in opposite directions |
| C. | v and B are perpendicular |
| D. | v and B are at an angle of \[45{}^\circ \] |
| Answer» D. v and B are at an angle of \[45{}^\circ \] | |
| 4922. |
A particle of charge q and mass m moving with a velocity v along the x-axis enters the region x > 0 with uniform magnetic field B along the \[\hat{k}\] direction. The particle will penetrate in this region in the x-direction upto a distance d equal to [MP PMT 1997] |
| A. | Zero |
| B. | \[\frac{mv}{qB}\] |
| C. | \[\frac{2mv}{qB}\] |
| D. | Infinity |
| Answer» C. \[\frac{2mv}{qB}\] | |
| 4923. |
A particle with \[{{10}^{-11}}\,coulomb\] of charge and \[{{10}^{-7}}\,kg\] mass is moving with a velocity of \[{{10}^{8}}\,m/s\] along the y-axis. A uniform static magnetic field \[B=0.5\,Tesla\] is acting along the x-direction. The force on the particle is [MP PMT 1997] |
| A. | \[5\times {{10}^{-11}}\,N\] along \[\hat{i}\] |
| B. | \[5\times {{10}^{3}}\] N along \[\hat{k}\] |
| C. | \[5\times {{10}^{-11}}\,N\] along \[-\hat{j}\] |
| D. | \[5\times {{10}^{-4}}\,N\] along \[-\hat{k}\] |
| Answer» E. | |
| 4924. |
-The charge on a particle Y is double the charge on particle X. These two particles X and Y after being accelerated through the same potential difference enter a region of uniform magnetic field and describe circular paths of radii \[{{R}_{1}}\] and \[{{R}_{2}}\] respectively. The ratio of the mass of X to that of Y is [MP PET 1997] |
| A. | \[{{\left( \frac{2{{R}_{1}}}{{{R}_{2}}} \right)}^{2}}\] |
| B. | \[{{\left( \frac{{{R}_{1}}}{2{{R}_{2}}} \right)}^{2}}\] |
| C. | \[\frac{R_{1}^{2}}{2R_{2}^{2}}\] |
| D. | \[\frac{2{{R}_{1}}}{{{R}_{2}}}\] |
| Answer» D. \[\frac{2{{R}_{1}}}{{{R}_{2}}}\] | |
| 4925. |
An electron is accelerated by a potential difference of 12000 volts. It then enters a uniform magnetic field of \[{{10}^{-3}}\,T\] applied perpendicular to the path of electron. Find the radius of path. Given mass of electron \[=9\times {{10}^{-31}}\,kg\] and charge on electron \[=1.6\times {{10}^{-19}}\,C\] [MP PET 1997] |
| A. | 36.7 m |
| B. | 36.7 cm |
| C. | 3.67 m |
| D. | 3.67 cm |
| Answer» C. 3.67 m | |
| 4926. |
A charged particle of mass m and charge q describes circular motion of radius r in a uniform magnetic field of strength B. The frequency of revolution is [MP PET 1997; RPET 2001] |
| A. | \[\frac{Bq}{2\pi m}\] |
| B. | \[\frac{Bq}{2\pi rm}\] |
| C. | \[\frac{2\pi m}{Bq}\] |
| D. | \[\frac{Bm}{2\pi q}\] |
| Answer» B. \[\frac{Bq}{2\pi rm}\] | |
| 4927. |
A current carrying long solenoid is placed on the ground with its axis vertical. A proton is falling along the axis of the solenoid with a velocity v. When the proton enters into the solenoid, it will |
| A. | Be deflected from its path |
| B. | Be accelerated along the same path |
| C. | Be decelerated along the same path |
| D. | Move along the same path with no change in velocity |
| Answer» E. | |
| 4928. |
An electron enters a magnetic field whose direction is perpendicular to the velocity of the electron. Then [MP PMT 1996; CBSE PMT 2003] |
| A. | The speed of the electron will increase |
| B. | The speed of the electron will decrease |
| C. | The speed of the electron will remain the same |
| D. | The velocity of the electron will remain the same |
| Answer» D. The velocity of the electron will remain the same | |
| 4929. |
An electron having charge \[1.6\times {{10}^{-19}}\,C\] and mass \[9\times {{10}^{-31}}\,kg\] is moving with \[4\times {{10}^{6}}\,m{{s}^{-1}}\] speed in a magnetic field \[2\times {{10}^{-1}}\,tesla\] in a circular orbit. The force acting on electron and the radius of the circular orbit will be [MP PET 1996; JIPMER 2000; BVP 2003] |
| A. | \[12.8\times {{10}^{-13}}N,\,1.1\times {{10}^{-4}}m\] |
| B. | \[1.28\times {{10}^{-14}}N,\,1.1\times {{10}^{-3}}m\] |
| C. | \[1.28\times {{10}^{-13}}N,\,1.1\times {{10}^{-3}}m\] |
| D. | \[1.28\times {{10}^{-13}}N,\,1.1\times {{10}^{-4}}m\] |
| Answer» E. | |
| 4930. |
A beam of ions with velocity \[2\times {{10}^{5}}\,m/s\] enters normally into a uniform magnetic field of \[4\times {{10}^{-2}}\,tesla\]. If the specific charge of the ion is \[5\times {{10}^{7}}\,C/kg\], then the radius of the circular path described will be [NCERT 1983; BVP 2003] |
| A. | 0.10 m |
| B. | 0.16 m |
| C. | 0.20 m |
| D. | 0.25 m |
| Answer» B. 0.16 m | |
| 4931. |
A beam of well collimated cathode rays travelling with a speed of \[5\times {{10}^{6}}\,m{{s}^{-1}}\] enter a region of mutually perpendicular electric and magnetic fields and emerge undeviated from this region. If \[|B|\,=0.02\,T\], the magnitude of the electric field is [Haryana CEE 1996] |
| A. | \[{{10}^{5}}\,V{{m}^{-1}}\] |
| B. | \[2.5\times {{10}^{8}}\,V{{m}^{-1}}\] |
| C. | \[1.25\times {{10}^{10}}\,V{{m}^{-1}}\] |
| D. | \[2\times {{10}^{3}}\,V{{m}^{-1}}\] |
| Answer» B. \[2.5\times {{10}^{8}}\,V{{m}^{-1}}\] | |
| 4932. |
An electron is moving on a circular path of radius r with speed v in a transverse magnetic field B. e/m for it will be [MP PMT 2003] |
| A. | \[\frac{v}{Br}\] |
| B. | \[\frac{B}{rv}\] |
| C. | Bvr |
| D. | \[\frac{vr}{B}\] |
| Answer» B. \[\frac{B}{rv}\] | |
| 4933. |
A charge + Q is moving upwards vertically. It enters a magnetic field directed to the north. The force on the charge will be towards [MP PMT 1995; AMU (Engg.) 2000] |
| A. | North |
| B. | South |
| C. | East |
| D. | West |
| Answer» E. | |
| 4934. |
A proton and an electron both moving with the same velocity v enter into a region of magnetic field directed perpendicular to the velocity of the particles. They will now move in circular orbits such that [MP PMT 1995] |
| A. | Their time periods will be same |
| B. | The time period for proton will be higher |
| C. | The time period for electron will be higher |
| D. | Their orbital radii will be same |
| Answer» C. The time period for electron will be higher | |
| 4935. |
A proton (or charged particle) moving with velocity v is acted upon by electric field E and magnetic field B. The proton will move undeflected if [MP PMT 1995, 2003; UPSEAT 2002; DPMT 2003] |
| A. | E is perpendicular to B |
| B. | E is parallel to v and perpendicular to B |
| C. | E, B and v are mutually perpendicular and \[v=\frac{E}{B}\] |
| D. | E and B both are parallel to v |
| Answer» D. E and B both are parallel to v | |
| 4936. |
A proton of mass \[1.67\times {{10}^{-27}}kg\] and charge \[1.6\times {{10}^{-19}}\,C\] is projected with a speed of \[2\times {{10}^{6}}\,m/s\] at an angle of \[60{}^\circ \] to the \[X-\]axis. If a uniform magnetic field of 0.104 Tesla is applied along \[Y-\]axis, the path of proton is [IIT-JEE 1995] |
| A. | A circle of radius = 0.2 m and time period \[\pi \times {{10}^{-7}}s\] |
| B. | A circle of radius = 0.1 m and time period \[2\pi \times {{10}^{-7}}s\] |
| C. | A helix of radius = 0.1 m and time period \[2\pi \times {{10}^{-7}}s\] |
| D. | A helix of radius = 0.2 m and time period \[4\pi \times {{10}^{-7}}s\] |
| Answer» D. A helix of radius = 0.2 m and time period \[4\pi \times {{10}^{-7}}s\] | |
| 4937. |
An electron and a proton enter region of uniform magnetic field in a direction at right angles to the field with the same kinetic energy. They describe circular paths of radius \[{{r}_{e}}\] and \[{{r}_{p}}\] respectively. Then [Manipal MEE 1995] |
| A. | \[{{r}_{e}}={{r}_{p}}\] |
| B. | \[{{r}_{e}}<{{r}_{p}}\] |
| C. | \[{{r}_{e}}>{{r}_{p}}\] |
| D. | \[{{r}_{e}}\] may be less than or greater than \[{{r}_{p}}\] depending on the direction of the magnetic field |
| Answer» C. \[{{r}_{e}}>{{r}_{p}}\] | |
| 4938. |
If a proton, deutron and \[\alpha -\]particle on being accelerated by the same potential difference enters perpendicular to the magnetic field, then the ratio of their kinetic energies is [MP PMT 2003; J & K CET 2005] |
| A. | 1 : 2 : 2 |
| B. | 2 : 2 : 1 |
| C. | 1 : 2 : 1 |
| D. | 1 : 1 : 2 |
| Answer» E. | |
| 4939. |
If a particle of charge \[{{10}^{-12}}\,coulomb\] moving along the \[\hat{x}-\]direction with a velocity \[{{10}^{5}}\,m/s\] experiences a force of \[{{10}^{-10}}\,newton\] in \[\hat{y}-\]direction due to magnetic field, then the minimum magnetic field is [MP PMT 1994] |
| A. | \[6.25\times {{10}^{3}}\,tesla\] in \[\hat{z}-\]direction |
| B. | \[{{10}^{-15}}\,tesla\] in \[\hat{z}-\]direction |
| C. | \[6.25\times {{10}^{-3}}\,tesla\] in \[\hat{z}-\]direction |
| D. | \[{{10}^{-3}}\,tesla\] in \[\hat{z}-\]direction |
| Answer» E. | |
| 4940. |
A proton enters a magnetic field of flux density \[1.5\,weber/{{m}^{2}}\] with a velocity of \[2\times {{10}^{7}}\,m/\sec \] at an angle of \[30{}^\circ \] with the field. The force on the proton will be [MP PET 1994 ; Pb. PMT 2004] |
| A. | \[2.4\times {{10}^{-12}}\,N\] |
| B. | \[0.24\times {{10}^{-12}}\,N\] |
| C. | \[24\times {{10}^{-12}}\,N\] |
| D. | \[0.024\times {{10}^{-12}}\,N\] |
| Answer» B. \[0.24\times {{10}^{-12}}\,N\] | |
| 4941. |
A magnetic field [MP PET 1994; Pb PMT 2003] |
| A. | Always exerts a force on a charged particle |
| B. | Never exerts a force on a charged particle |
| C. | Exerts a force, if the charged particle is moving across the magnetic field lines |
| D. | Exerts a force, if the charged particle is moving along the magnetic field lines |
| Answer» D. Exerts a force, if the charged particle is moving along the magnetic field lines | |
| 4942. |
An electron is travelling horizontally towards east. A magnetic field in vertically downward direction exerts a force on the electron along [EAMCET 1984] |
| A. | East |
| B. | West |
| C. | North |
| D. | South |
| Answer» E. | |
| 4943. |
If a proton is projected in a direction perpendicular to a uniform magnetic field with velocity v and an electron is projected along the lines of force, what will happen to proton and electron [DPMT 1979] |
| A. | The electron will travel along a circle with constant speed and the proton will move along a straight line |
| B. | Proton will move in a circle with constant speed and there will be no effect on the motion of electron |
| C. | There will not be any effect on the motion of electron and proton |
| D. | The electron and proton both will follow the path of a parabola |
| Answer» C. There will not be any effect on the motion of electron and proton | |
| 4944. |
A deutron of kinetic energy 50 keV is describing a circular orbit of radius 0.5 metre in a plane perpendicular to magnetic field \[\overrightarrow{B}\]. The kinetic energy of the proton that describes a circular orbit of radius 0.5 metre in the same plane with the same \[\overrightarrow{B}\] is [CBSE PMT 1991] |
| A. | 25 keV |
| B. | 50 keV |
| C. | 200 keV |
| D. | 100 keV |
| Answer» E. | |
| 4945. |
A strong magnetic field is applied on a stationary electron, then [BIT 1989; MP PMT 1995; CPMT 1999] |
| A. | The electron moves in the direction of the field |
| B. | The electron moves in an opposite direction |
| C. | The electron remains stationary |
| D. | The electron starts spinning |
| Answer» D. The electron starts spinning | |
| 4946. |
A uniform magnetic field acts at right angles to the direction of motion of electrons. As a result, the electron moves in a circular path of radius 2 cm. If the speed of the electrons is doubled, then the radius of the circular path will be [CBSE PMT 1991] |
| A. | 2.0 cm |
| B. | 0.5 cm |
| C. | 4.0 cm |
| D. | 1.0 cm |
| Answer» D. 1.0 cm | |
| 4947. |
A uniform magnetic field B is acting from south to north and is of magnitude 1.5 \[Wb/{{m}^{2}}\]. If a proton having mass \[=1.7\times {{10}^{-27}}\,kg\] and charge \[=1.6\times {{10}^{-19}}\,C\] moves in this field vertically downwards with energy 5 MeV, then the force acting on it will be [Pb. PMT 2002] |
| A. | \[7.4\times {{10}^{12}}\,N\] |
| B. | \[7.4\times {{10}^{-12}}\,N\] |
| C. | \[7.4\times {{10}^{19}}\,N\] |
| D. | \[7.4\times {{10}^{-19}}\,N\] |
| Answer» C. \[7.4\times {{10}^{19}}\,N\] | |
| 4948. |
A uniform electric field and a uniform magnetic field are produced, pointed in the same direction. An electron is projected with its velocity pointing in the same direction [NCERT 1980; CBSE PMT 1993; JIPMER 1997; AIEEE 2005] |
| A. | The electron will turn to its right |
| B. | The electron will turn to its left |
| C. | The electron velocity will increase in magnitude |
| D. | The electron velocity will decrease in magnitude |
| Answer» E. | |
| 4949. |
An \[\alpha -\]particle travels in a circular path of radius 0.45 m in a magnetic field \[B=1.2\,Wb/{{m}^{2}}\] with a speed of \[2.6\times {{10}^{7}}\,m/\sec \]. The period of revolution of the \[\alpha -\]particle is |
| A. | \[1.1\times {{10}^{-5}}\,\sec \] |
| B. | \[1.1\times {{10}^{-6}}\sec \] |
| C. | \[1.1\times {{10}^{-7}}\,\sec \] |
| D. | \[1.1\times {{10}^{-8}}\,\sec \] |
| Answer» D. \[1.1\times {{10}^{-8}}\,\sec \] | |
| 4950. |
A proton (mass \[=1.67\times {{10}^{-27}}\,kg\] and charge \[=1.6\times {{10}^{-19}}\,C)\] enters perpendicular to a magnetic field of intensity 2 \[weber/{{m}^{2}}\] with a velocity \[3.4\times {{10}^{7}}\,m/\sec \]. The acceleration of the proton should be [DPMT 1999] |
| A. | \[6.5\times {{10}^{15}}\,m/{{\sec }^{2}}\] |
| B. | \[6.5\times {{10}^{13}}\,m/{{\sec }^{2}}\] |
| C. | \[6.5\times {{10}^{11}}\,m/{{\sec }^{2}}\] |
| D. | \[6.5\times {{10}^{9}}\,m/{{\sec }^{2}}\] |
| Answer» B. \[6.5\times {{10}^{13}}\,m/{{\sec }^{2}}\] | |