R4RIN – MCQs, Mock Tests | IIT JEE IIT JEE Magnetic Effect Of Current And Magnetism

A charged particle moving in a uniform magnetic field and losses 4% of its KE. The radius of curvature of its path changes by:

1. 2%
2. 4%
3. 10%
4. none of these

✅ Correct Answer: 1

wo charged particles each of mass m and charge q are projected in a uniform magnetic field B with the same speed as such planes of motion of particles are perpendicular to magnetic field B then:

1. they move on circular path of same radii
2. the magnetic forces on them are same to each other
3. the kinetic energies of particles are same to each other
4. all of the above

✅ Correct Answer: 4

The earths magnetic field at a certain point is 0.70 gauss. This field is to be annulled by the magnetic field at the centre of a circular conducting loop 5.0 cm in radius. The required current is about:

1. 0.66 A
2. 5.6 A
3. 0.28 A
4. 2.8 A

✅ Correct Answer: 2

If an electron and proton having same momenta enter perpendicularly to a magnetic field then:

1. curved path of electron and proton will be same
2. (ignoring the sense of revolution)
3. they will move undeflected
4. path of proton is more curved

✅ Correct Answer: 1

A charged particle enters a region of non-uniform field and eventually comes out of it. As it emerges its

1. speed is greater as compared to the speed at entry point
2. velocity remains unchanged velocity may change but
3. curved path of electron is more curved than that of proton
4. speed remain unchanged speed cannot be estimated as data is insufficient

✅ Correct Answer: 3

A particle having positive charge is released from rest in an electric field acting horizontally and moves under the influence of both electric field and gravity Which one of the following quantities connected with the charge particles continuously increases with time?

1. Electric potential energy
2. Gravitational potential energy
3. Electrical charge
4. Kinetic energy

✅ Correct Answer: 4

A charged particle placed in a uniform magnetic field experiences:

1. A force in the direction of the field
2. A force opposite to the direction of the field
3. A force perpendicular to the direction of the field
4. None

✅ Correct Answer: 4

If the current is flowing clockwise in a circular coil the direction of lines of force inside the coil is:

1. towards you
2. away from you
3. towards the centre along the radius
4. away from the centre along the radius

✅ Correct Answer: 2

A beam of protons is deflected side ways. Could this deflection be caused by:

1. magnetic field only
2. electric field only
3. either electric or magnetic field
4. both electric and magnetic fields

✅ Correct Answer: 3

A positive charge is moving upwards in a magnetic field which is towards north. The particle will be deflected towards:

1. east
2. west
3. north
4. south

✅ Correct Answer: 2

A current loop placed in a magnetic field because like a:

1. magnetic dipole
2. magnetic substance
3. magnetic pole
4. all are true

✅ Correct Answer: 1

The strength of the magnetic field around a straight wire:

1. is same everywhere around the wire obeys inverse square law
2. is directly proportional to the square of the distance
3. from the wire
4. none of the above

✅ Correct Answer: 1

As per Amperes law the line integral of the magnetic intensity around a closed path is equal to:

1. the charge enclosed
2. the current enclosed
3. the energy enclosed
4. the flux enclosed

✅ Correct Answer: 2

A positive charge is released from the origin at a place where uniform electric field E and a uniform magnetic field B exist along the positive y-axis and positive z-axis respectively then:

1. initially the charged particle tends to move along positive z-axis
2. initially the charged particle tends to move along negative y-direction
3. initially the charged particle tends to move along positive y-direction
4. the charged particle moves in y-z plane

✅ Correct Answer: 4

Two protons are moving with same velocity in magnetic field of same magnitude then:

1. magnetic force on protons may be zero
2. magnetic force on both must be same to each other magnetic force on both
3. may or may not be same to each other
4. both A and C are correct

✅ Correct Answer: 4

When a charged particle moves in a magnetic field its KE always:

1. increases
2. magnetic force on both must be same to each other
3. remains constant increases or decreases
4. which depends on direction of projection of particle

✅ Correct Answer: 3

The time period of a charged particle undergoing a circular motion in a uniform magnetic field is independent of its:

1. decreases
2. magnetic force on both
3. charge
4. magnetic induction

✅ Correct Answer: 1

Imagine that you are seated in a room and there is a uniform magnetic field pointing vertically downwards in it. At the centre of the room an electron is projected horizontally with a certain speed. Discuss the speed and the path of the electron in this field.

1. Electron moves in anticlockwise path
2. Electron moves in clockwise path
3. Electron moves left wards
4. Electron moves right wards

✅ Correct Answer: 2

If a current is passed through a spring then the spring will:

1. expand
2. compress
3. remain same
4. none of these

✅ Correct Answer: 2

A charged particle moves in a magnetic field in a plane perpendicular to the magnetic field. The orbital magnetic moment of circulating charge is direction:

1. parallel to magnetic field
2. against the magnetic field
3. perpendicular to magnetic field
4. none of the above

✅ Correct Answer: 2

3.In a region steady and uniform electric and magnetic fields are present. These two fields are parallel to each other. A charged particle is released from rest in this region. The path of the particle will be a:

1. helix
2. straight line
3. ellipse
4. circle

✅ Correct Answer: 2

Mark correct option or options

1. Electric field and magnetic field are basically independent
2. Electric field and magnetic field are two aspects of the electromagnetic field
3. Electric field and magnetic field may be produced by charge in rest
4. Both A and C are correct

✅ Correct Answer: 2

A proton moving in a straight line enters a strong magnetic field along the field direction How will its path and velocity change?

1. Path is circular but speed constant
2. Path is same but velocity increase
3. Path is same and velocity remains constant
4. Path is same but motion is retarded

✅ Correct Answer: 3

A long wire carries a current of 20 A along the axis of a solenoid the field due to the solenoid is 4 mT. The resultant field at a point 3 mm from the solenoid axis is:

1. 1.33 mT
2. 4.2 mT
3. 2.1 mT
4. 8.4 mT

✅ Correct Answer: 2

A conducting loop carrying a current is placed in a non-uniform magnetic field perpendicular to the plane of loop. Then:

1. loop must experience force
2. loop may experience torque
3. loop must experience torque
4. none of the above

✅ Correct Answer: 1

A uniform electric field and a uniform magnetic field are acting along the same direction in a certain region. If an electron is projected along the direction of the fields with a certain velocity then:

1. its velocity will decrease
2. its velocity will increase
3. it will turn towards right of directions of motion
4. it will turn towards left of direction of motion

✅ Correct Answer: 1

The direction of magnetic field at a point due to an infinitely long wire carrying current is:

1. parallel to the current
2. antiparallel to the current
3. along the perpendicular drawn from a point on the wire
4. perpendicular to the plane containing the conductor and the point

✅ Correct Answer: 4

If the p. d. between two plates separated by a distance d be V then electric field E is equal to

1. Vd
2. d / V
3. d / V
4. V/ d

✅ Correct Answer: 4

A charged particle moves through a magnetic field in a direction perpendicular to it then

1. the speed of the particle remains unchanged
2. the direction of particle remains unchanged
3. acceleration remains unchanged
4. velocity remains unchanged

✅ Correct Answer: 1

A length of wire carries a steady current. It is bent to form a circular coil of one turn only. The same length is now bent more sharply to give a double loop of smaller radius. The magnetic field at the centre caused by the same current is

1. A half of its first value
2. Unaltered
3. A quarter of its first value
4. Four times its first value

✅ Correct Answer: 4

The magnetic induction at a point due to a long straight conductor carrying current is independent of

1. its length
2. the current coil
3. the distance from the given point
4. all of the above

✅ Correct Answer: 1

A vertical straight conductor carries a current vertically upwards. A point P lies to the east of it at a it at the same distance. The magnetic field at P is

1. greater as at Q
2. same as at Q
3. less than at Q
4. greater or less than at Q depending upon the strength of the current

✅ Correct Answer: 1

You are facing a coil through which a current I is passing in the clockwise direction. The face of the coil towards you is a

1. notth pole
2. monopole
3. dipole
4. south pole

✅ Correct Answer: 4

Two infinitely long thin insulated straight wires lie in x-y plane along the x and y-axis respectively. Each wire carries a current I respectively in the positive X-direction and positive Y-direction. The magnetic field will be zero at all points on the straight line

1. y = x
2. y = - 2x
3. y = x -4
4. y = - x + 5

✅ Correct Answer: 1

A bar magnet is oscillating in Earths magnetic field with a period T. What happens to its period and motion if its mass is quadrupled ?

1. Motion remains simple harmonic with time period = T / 2
2. Motion remains simple harmonic with time period = 2 T
3. Motion remains simple harmonic with time period = 4 T
4. Motion remains simple harmonic and period remains nearly constant

✅ Correct Answer: 2

A charged particle moving at right angle to the uniform magnetic field follows

1. linear path
2. parabolic path
3. circular path
4. hyperbolic path

✅ Correct Answer: 3

The direction of force on a conductor carrying current in a magnetic fields is given by

1. Flemings right hand rule
2. Fleming s left hand rule
3. Savart s rule
4. Laplace rule.

✅ Correct Answer: 2

A sensitive magnetic instrument can be shielded very effectively from outside magnetic fields by placing it inside a box of

1. metal of high conductivity soft iron of high
2. permeability
3. wood
4. plastic material

✅ Correct Answer: 2

To measure charge the galvanometer used is

1. an ammeter
2. ballistic galvanometer
3. voltmeter
4. moving coil galvanometer

✅ Correct Answer: 2

A moving coil galvanometer used is

1. dead beat type
2. oscillatory
3. ballistic
4. None of these

✅ Correct Answer: 2

The permeanility of a material is 0.7421. This material is

1. Diamagnetic
2. Paramagnetic
3. Ferromagnetic
4. None of these.

✅ Correct Answer: 1

The restoring couple in the moving coil galvanometer is because of

1. magnetic field
2. material of the coil
3. twist produced in the suspension
4. current in the coil

✅ Correct Answer: 3

The lines of force around an infinitely long conductor carrying current are

1. perpendicular to the conductor
2. inclined to the conductor
3. parallel to the conductor
4. concentric circles

✅ Correct Answer: 4

The south pole of a magnetic is placed on the axis of circular coil carrying current in the clockwise direction . It experiences a force of

1. attraction
2. epulsion
3. neither attraction nor repulsion
4. both attraction and repulsion.

✅ Correct Answer: 2

Argon Krypton Xenon Radon are the examples of

1. non-magnetics
2. ferromagnetics
3. paramagnetics
4. diamagnatics

✅ Correct Answer: 4

Cosmic rays are said to be highly energetic protons hitting the earth on account of earths magnetic field. They should get deflected to

1. North
2. South
3. East
4. West

✅ Correct Answer: 3

If the magnetic moment of the atoms of a substance is zero the substance is called

1. diamagnetic
2. paramagnetic
3. ferromagnetic
4. anti-ferromagnetic field

✅ Correct Answer: 1

When a charged particle moves inside a transverse electric field the path traced out by it is

1. a circle
2. a straight line
3. elliptical
4. parabola.

✅ Correct Answer: 4

A charged particle moving at right angle to the electric field follows

1. parabolic path
2. circular path
3. linear path
4. elliptical path

✅ Correct Answer: 2

In dead beat galvanometer the frame on which coil is wound is

1. semi conductor
2. metallic
3. non-metallic
4. of phosphor bronze

✅ Correct Answer: 3

If a long copper rod carries a direct current the magnetic field associated with the current will be

1. inside the rod only
2. outside the rod only
3. both inside and outside the rod
4. neither inside nor outside the rod.

✅ Correct Answer: 3

The S-pole of a magnet is placed on the axis of a circular coil carrying current in ant-clockwise direction. It experiences a force of

1. attraction
2. repulsion
3. neither attraction nor repulsion
4. both attraction and repulsion

✅ Correct Answer: 1

If proton are shot perpendicular toa magnetic field

1. Magnetic field will have no influence on the motion of protons
2. Protons will continue to move in the same direction but will gain momentum
3. Protons will continue to move in the opposite directions but will gain momentum
4. They will bend in an are of a circle.

✅ Correct Answer: 4