NEET IIT magnetic effects current,ncert CBSE Class12 physics solutions

# Magnetic Effects of Current Mock Test-1

Questions No:1

Assertion: Flux of magnetic field B through a closed surface is equal to zero.

Reason: Magnetic field lines are closed curves. They don’t have beginning or end.

[A] If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
[B] If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
[C] If Assertion is true but Reason is false.
[D] If Assertion is false but Reason is true.
[E]If both Assertion and Reason are false

Questions No:2

Assertion: A flexible wire loop of irregular shape carrying current when placed in a uniform external magnetic field acquires a circular shape.

Reason: For a given perimeter circular shape is having the greatest area.

[A] If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
[B] If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
[C] If Assertion is true but Reason is false.
[D] If Assertion is false but Reason is true.
[E]If both Assertion and Reason are false

Questions No:3

Assertion: If a charged particle is projected in a region where B is perpendicular to velocity of projection, then the net force acting on the particle is independent of its mass.

Reason: The particle is performing uniform circular motion, and force acting on it is $\frac{mv^2}{r}$

[A] If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
[B] If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
[C] If Assertion is true but Reason is false.
[D] If Assertion is false but Reason is true.
[E]If both Assertion and Reason are false

Questions No:4

Assertion: In non uniform magnetic field speed of a charged particle varies.

Reason: Work done by magnetic force on a charged particle is always zero.

[A] If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
[B] If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
[C] If Assertion is true but Reason is false.
[D] If Assertion is false but Reason is true.
[E]If both Assertion and Reason are false

Questions No:5

Assertion: Path of a charged particle in uniform magnetic field cannot be a parabola if no other forces (other than magnetic force) are acting on the particle.

Reason: For parabolic path a constant acceleration is required.

[A] If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
[B] If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
[C] If Assertion is true but Reason is false.
[D] If Assertion is false but Reason is true.
[E]If both Assertion and Reason are false

Questions No:6

Assertion: If a charged particle enters from outside in uniform magnetic field then it will keep on rotating in a circular path.

Reason: Magnetic force is always perpendicular to velocity vector.

[A] If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
[B] If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
[C] If Assertion is true but Reason is false.
[D] If Assertion is false but Reason is true.
[E]If both Assertion and Reason are false

Questions No:7

Assertion Magnetic field [B] and electric field [E]are present in a region. Net force on a charged particle in this region is zero if
E =B x v

Reason: $\frac{E}{B}$ — has the dimensions of velocity. B
[A] If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
[B] If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
[C] If Assertion is true but Reason is false.
[D] If Assertion is false but Reason is true.
[E]If both Assertion and Reason are false

Questions No:8

Assertion: An alpha particle and a deuteron having same kinetic energy enter in a uniform magnetic field perpendicular to the field. Then radius of circular path of alpha particle will be more.

Reason: $\frac{q}{m}$ ratio of an α particle is more than the $\frac{E}{B}$ratio of a deutron.

[A] If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
[B] If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
[C] If Assertion is true but Reason is false.
[D] If Assertion is false but Reason is true.
[E]If both Assertion and Reason are false

Questions No:9

Assertion: A charged particle is rotating in a circular path in uniform magnetic field. Then plane of circle is perpendicular to the magnetic field.

Reason: Circular motion is a two dimensional motion.

[A] If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
[B] If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
[C] If Assertion is true but Reason is false.
[D] If Assertion is false but Reason is true.
[E]If both Assertion and Reason are false

Questions No:10

Assertion: At the centre of a circular current carrying loop (I1), there is an infinitely long straight current carrying wire (I2) perpendicular to the plane of the circle. Then magnetic force of attraction between two is zero.

Reason: Magnetic field of I1 at centre is inwards, parallel to I2

[A] If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
[B] If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
[C] If Assertion is true but Reason is false.
[D] If Assertion is false but Reason is true.
[E]If both Assertion and Reason are false

Questions No:11

Assertion: If velocity of charged in a uniform magnetic field at some instant is (a1i- a2j) and at some other instant is (b1i+ b2j) , then
${a_1}^2+{a_2}^2={b_1}^2+{b_2}^2$

Reason: Magnetic force cannot change velocity of a charged particle.

[A] If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
[B] If both Assertion and Reason are true but Reason is not correct explanation of Assertion.
[C] If Assertion is true but Reason is false.
[D] If Assertion is false but Reason is true.
[E]If both Assertion and Reason are false

Questions No:12

A charged particle enters in a uniform magnetic field perpendicular to it. Now match the following two columns

Column 1                                 Column II

[A] Speed of the particle (P) Is constant
[B] Velocity of the particle (q) Is not constant
[C] Acceleration of the particle (r) Is maximum
[D] Force on the particle (s) Is minimum

Questions No:13

A charged particle is rotating in uniform circular motion in a uniform magnetic field. Let r = radius of circle, v = speed of particle, K = kinetic energy, a = magnitude of acceleration ,P = magnitude of linear momentum,(q/m)=α = specific charge and ω = angular speed. Then match the following two columns.

Column I—————— Column II

[A] If v is doubled (p) r will become two times
[B] If K s doubled (q) ω will become two times
[C] If P is doubled (r) swill become two times
[D] If a is doubled (s) None

Questions No: 14

Two particles A and B having equal charges +6 C, after being accelerated through the same potential difference, enter a region of uniform magnetic field and describe circular paths of radii 2 cm and 3 cm respectively. The ratio of mass of A to that of B is

[A] 4/9
[B] 9/5
[C] 1/2
[D] 1/3

Questions No:15

The path of a charged particle in a uniform magnetic field, when the velocity and the magnetic field are perpendicular to each other is a

[A] circle
[B] parabola
[C] helix
[D] straight line

Questions No:16

A proton travelling at 230 w.r.t. the direction of a magnetic field of strength 2.6 mT experiences a magnetic force of 6.5 x10-17 N. What is the speed of the proton?
[A]2×105 ms-1
[B]4×105 ms-1
[C]6×105 ms-1
[D]6×10-5 ms-1

Questions No:17

What uniform magnetic field applied perpendicular to a beam of electrons moving at 1.3 x 106 ms-1, is required to make the electrons travel in a circular arc of radius 0.35 m?

[A] 2.1 x10-5 G
[B] 6×10-5 T
[C] 2.1 x10-5 T
[D] 6x 10-5 G

Questions No:18

A uniform electric field and a uniform magnetic field are acting along 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

[A] speed will decrease
[B] speed will increase
[C] will turn towards left of direction of motion
[D] will turn towards right of direction a motion

Questions No:19

An electron is accelerated under a potential difference of 182 V. The maximum velocity of electron will be (Charge of electron is 1.6 x 10-19 C and its mass is 9.1 x10-31 kg )

[A] 5.65×106 m-1
[B] 4×106 m-1
[C] 8×106 m-1
[D] 16 x 10-6m-1

Questions No:20

A charged particle enters into a uniform magnetic field with velocity v0 perpendicular to it, the length of magnetic field is x =$\sqrt\frac{3}{2})\ R, where R is the radius of the circular path of the particle in the field. The magnitude of change in velocity of the particle when it comes out of the field is [A]2v0 [B]\( \frac{v_0}{2}$

[C]$\frac{\sqrt{3}v_0}{2}$

[D]v0

Questions No:21

A square frame of side 1 m carries a current I, produces a magnetic field B at its centre. The same current is passed through a circular coil having the same perimeter as the square. The magnetic field at the centre of the circular coil is B. The ratio B/ B’ is

[A]$\frac{8}{π^2}$

[B]$\frac{8\sqrt{2}}{π^2}$

[C]$\frac{16}{π^2}$

[D]$\frac{16}{\sqrt{2}π^2}$

Questions No:22

A long straight wire along the z-axis carries a current “I “in the negative Z-direction. The magnetic vector field B at a point having coordinates (X,Y) in the Z = 0 plane is..

[A]$\frac{μ_0I(Yi-Xj)}{2π(x^2+Y^2)}$

[B]$\frac{μ_0I(Xi+Yj)}{2π(x^2+Y^2)}$

[C]$\frac{μ_0I(Xj-Yi)}{2π(x^2+Y^2)}$

[D]$\frac{μ_0I(Xi-Yj)}{2π(x^2+Y^2)}$