Magnetic effect of current practice · Mixed difficulty

An electron of mass $m$ is accelerated by a d.c. potential difference $V$ and then subjected to a transverse magnetic field $B$, The trajectory of the electron will be a circle of radius

Assertion: Free electron always keep on moving in a conductor even then no magnetic force act on them in magnetic field unless a current is passed through it.

Reason: The average velocity of free electron is zero.

A wire of length ' $L$ ' carries current ' $I$ ' along $x$ axis, A magnetic field $B=B_0(\hat{\mathbf{i}}-\hat{\mathbf{j}}-\hat{\mathbf{k}}) \mathbf{T}$ acts on the wire. The magnitude of magnetic force acting on the wire is

Assertion: The energy of charged particle moving in a uniform magnetic field does not change.

Reason: Work done by magnetic field on the charge is zero.

When a charged particle enters uniform
magnetic field its kinetic energy

A straight wire carries a current of $3 \mathrm{~A}$. Calculate the magnitude of the magnetic field at a point $10 \mathrm{~cm}$ away from the wire.

A charged particle enters a uniform magnetic
field with a certain speed at right angles to it.
In the magnetic field a change could occur in
its

A very long conductor carries a current of 1 A. The magnetic field at a point whose distance is $0.1 \mathrm{~m}$ from one end of the conductor is (in ' $T$ ')

A solenoid is $2.0 \mathrm{~m}$ long and $3.0 \mathrm{~cm}$ in diameter. It has 5 layers of winding of 1000 turns each and carries a current of $5.0 \mathrm{~A}$. What is the magnetic field at the centre? Use the standard value of $\mu_0$.

A current carrying loop lies on a smooth horizontal plane. Then,

Assertion (A): The range of given voltmeter can be both increased and decreased.

Reason (R): By adjusting the value of resistance in series with galvanometer the range of voltmeter can be adjusted.

A negatively charged particle projected
towards east is deflected towards north by a
magnetic filed. The field may be:

The formula for magnetic field of a certain component is given by $B=\frac{\mu_0 N i}{2 \pi r}$

Where, $\mathbf{N}=$ total number of turns
$i=$ current through it
${r}=$ radius.

The component is

An electron is projected with uniform velocity along the axis of a current carrying long solenoid. Which of the following is true?

An electron having kinetic energy $10 \mathrm{eV}$ is circulating in a path of radius $0.1 \mathrm{~m}$ in an external magnetic field of intensity $10^{-4} \mathrm{~T}$. The speed of the electron will be

Two beams of electrons are moving parallel to each other then magnetic force acting between them is

A circular coil of diameter $7 {~cm}$ has 24 turns of wire carrying current of $0.75 {~A}$. The magnetic moment of the coil is

The force on a conductor of length $l$ placed in a magnetic field of magnitude $B$ and carrying a current $i$ is given by ( $\theta$ is the angle, the conductor makes with the direction of $B$ ) :

A proton and an $\alpha \mathrm{ - }$ particle (with their masses in the ratio of 1 : 4 and charges in the ratio of 1 : 2) are accelerated from rest through a potential difference V. If a uniform magnetic field B is set up perpendicular to their velocities, the ratio of the radii ${r_p}:{r_\alpha }$ of the circular paths described by them will be

A constant voltage is applied to a series $\mathrm{R}-\mathrm{L}$ circuit by closing the switch. The voltage across inductor $(\mathrm{L}=2 \mathrm{H})$ is $20 \mathrm{~V}$ at $\mathrm{t}=0$ and drops to $5 \mathrm{~V}$ at $20 \mathrm{~ms}$. The value of $\mathrm{R}$ in $\Omega$ is:

A charged particle moves through a magnetic
field in a direction perpendicular to it. Then the

The frequency of the charged particle circular at right angles to a uniform magnetic field does not depend upon the

In a chamber, a uniform magnetic field of $6.5\,\mathrm{G}(1\,\mathrm{G}=$ $10^{-4} \mathrm{~T}$ ) is maintained. An electron is shot into the field with a speed of $4.8 \times 10^6 \mathrm{~ms}^{-1}$ normal to the field. Explain why the path of the electron is a circle. Determine the radius of the circular orbit. Given that $e=1.6 \times 10^{-19} \mathrm{C},\quad m_e=9.1 \times 10^{-31} \mathrm{~kg}$.

Biot-Savart law indicates that the moving electrons (velocity ${v}$ ) produce a magnetic field ${B}$ such that

In order to increase the sensitivity of galvanometer

A galvanometer coil has a resistance of $10 \Omega$ and the ammeter shows full scale deflection for a current of $1 {~mA}$. The shunt resistance required to convert the galvanometer into an ammeter of range $0.100 {~mA}$ is about

The intensity of magnetic field due to current I in a long straight wire is proportional to

Two particles having same charge and KE enter at right angles into the same magnetic field and travel in circular paths of radii 2 cm and 3 cm respectively. The ratio of their masses is

A proton and an alpha particle both enter a region of uniform magnetic field $\mathrm{B}$, moving at right angles to the field $\mathrm{B}$. If the radius of circular orbits for both the particles is equal and the kinetic energy acquired by proton is $\mathrm{1}\,\mathrm{MeV}$, the energy acquired by the alpha particle will be:

When a current carrying conductor is placed in magnetic field,then: