Magnetic effect of current practice · Mixed difficulty

An electron enters a magnetic field along perpendicular direction. Following quantity will remain constant

The electric current in a circular coil of four turns produces a magnetic induction $32 \mathrm{~T}$ at its centre. The coil is unwound and is rewound into a circular coil of single turn, the magnetic induction at the centre of the coil by the same current will be

When $\sqrt 3 \;ampere$ current is passed in a tangent galvanometer, there is a deflection of $30^\circ$ in it. The deflection obtained when $3\;amperes$ current is passed, is

At the mid-point along the length of a long solenoid, the magnetic field is equal to $X$. If the length of the solenoid is doubled and the current is reduced to half the field at the new mid-point will be nearest to

An electron, a proton and an alpha particle having the same kinetic energy are moving in circular orbits of radii ${r_e},{r_p},{r_\alpha }$ respectively, in a uniform magnetic field B. the relation between ${r_e},{r_p},{r_\alpha }$ is

If a shunt of $15\,\,\Omega$ is connected with a galvanometer of resistance $60\,\,\Omega$, then the resistance necessary to be connected in series with circuit for keeping the main current constant.

An electrically charged particle enters into a uniform magnetic induction field in a direction perpendicular to the field with a velocity $\mathrm{v}.$ Then, it travels

Assertion (A) : An electron and a proton are accelerated by same potential difference and then enter in uniform transverse magnetic field. The radii of the two will be different.

Reason (R) : Charges on them are different.

Assertion: Cyclotron does not accelerate electron.

Reason: Mass of the electron is very small.

A circular coil of 200 turns has a radius of $10 \mathrm{~cm}$ and carries a current of $2.0 \mathrm{~A}$. (a) Find the magnitude of the magnetic field $\vec{B}$ at the centre of the coil. (b) At what distance from the centre along the axis of the coil will the field $B$ drop to half its value at the centre? $(\sqrt[3]{4}=1.5874 \ldots)$

Two straight parallel wires carry currents of $200\,\,{\mkern 1mu} mA\,\,{\mkern 1mu} \mathrm{and}\,\,\,{\mkern 1mu} 1A$ in opposite directions. If the wires are 20 cm apart, the distance of the neutral point from the $1A$ wire is (in cm)

A long cylindrical wire kept along ${Z}$-axis carries a current of density $\bar{J}=J_0 r \hat{k}$ where $J_0$ is a constant and ${r}$ is the radial distance from the axis of the cylinder. The magnetic induction ${B}$ inside the conductor at a distance ${d}$ from the axis of the cylinder is

A solenoid, of length $1.5 \mathrm{~m}$, has a radius of $1.5 \mathrm{~cm}$ and has a total of 1500 turns wound on it. It carries a current of $3 \mathrm{~A}$. Calculate the magnitude of the axial magnetic field inside the solenoid. If an electron were to move with a speed of $2 \times 10^4 \mathrm{~ms}^{-1}$ along the axis of this current carrying solenoid, what would be the force experienced by this electron?

Given the fact that
A) Magnetic field exerts force only on a moving
charge
B) Electric field exerts force on both stationary
and moving charge
C) Magnetic field exerts force on charge moving
parallel to the direction of the field.
Which of the following is true?

Given below are two statements:

Statement I: If the number of turns in the coil of a moving coil galvanometer is doubled then the current sensitivity becomes double.

Statement II: Increasing current sensitivity of a moving coil galvanometer by only increasing the number of turns in the coil will also increase its voltage sensitivity in the same ratio

In the light of the above statements, choose the correct answer from the options given below:

A charged particle moving in a magnetic field
is increased in its velocity, then its radius of the
circle

Statement-1: Net force on a current carrying loop in a non-uniform magnetic field must be non-zero.
Statement-2: Force on a current carrying wire of length $\vec{dl}$ placed in magnetic field $\overrightarrow{{B}}$ is given by $\overrightarrow{d {F}}=i \vec{dl} \times \overrightarrow{{B}}$

A particle of charge $q$ moves in a circle of radius $r$ with speed $v$. Treating the circular path as a current loop with an average current, find the maximum torque exerted on the loop by a uniform field of magnitude $B$.

Magnetic fields at two points on the axis of a circular coil at a distance of 0.05m and 0.2m from the centre are in the ratio 8 : 1. The radius of coil is

A long straight solenoid with cross sectional radius ' $a$ ' and number of turns per unit length ' $n$ ' has a current varying width time as $I\left(\mathrm{As}^{-1}\right)$. The magnitude of the electric field as a function of distance ' $r$ ' from the solenoid axis is

A cyclotron is used to accelerate :

A current carrying circular coil, suspended
freely in a uniform external magnetic field
orients to a position of stable equilibrium. In
this state:

A wire of length $2 \mathrm{~m}$ carrying a current of $1 \mathrm{~A}$ is bent to form a circle, the magnetic moment of the coil is

For a long current carrying solenoid having inside magnetic field is $0.6 \mathrm{~T}$. Then find the magnetic energy per unit volume is

Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason
R.
Assertion A: For measuring the potential difference across a resistance of $600 \,\Omega$, the
voltmeter with resistance $1000 \,\Omega$ will be preferred over voltmeter with resistance $4000\,\Omega.$
Reason R: Voltmeter with higher resistance will draw smaller current than voltmeter with lower resistance.
In the light of the above statements, choose the most appropriate answer from the options given below:

An electron is moving with velocity $10^7 \mathrm{~m} / \mathrm{s}$ on a circular path of radius $0.57 \mathrm{~cm}$ in a magnetic field of $10^{-2} \mathrm{~Wb} / \mathrm{m}^2$. Find the value of e/m for electron in $\text { coulomb } / \mathrm{kg}$.

A $+6 \mu \mathrm{C}$ point charge is moving at a constant velocity of $8 \times 10^6 \mathrm{~ms}^{-1}$ in the $+y$ direction, relative to a reference frame. At the instant when the point charge is at the origin of this reference frame, what is the magnetic field vector it produces at the following points?
(a) $x=0.500 \mathrm{~m}, y=0, z=0$, and
(b) $x=0, y=-0.500 \mathrm{~m}, z=0$.

The magnetic field due to current carrying a circular loop of radius $5 \mathrm{~cm}$ at a point on the axis at a distance of $12 \mathrm{~cm}$ from the center is $250 \mu \mathrm{T}$. The magnetic field at the center of the loop is

Consider a wire carrying a steady current, $i$ placed in a uniform magnetic field ${B}$ perpendicular to its length. Consider the charges inside the wire. It is known that magnetic forces do no work. This implies that,

Inside a cyclotron, a charged particle is
subjected to both an electric field and a
magnetic field. It gains kinetic energy due to