Magnetic Field

A beam of  $\alpha$  particles projected along +x – axis, experiences a force due to a magnetic field along the +y – axis. What is the direction of the magnetic field?
 

An electron moves around the nucleus in a hydrogen atom of radius $0.51 \stackrel{\circ }{\mathrm{A}}$, with a velocity of  $2\times {10}^5 \mathrm{m} {\mathrm{s}}^{-1}$. Calculate the following :

(i) The equivalent current due to orbital motion of electron.

(ii) The magnetic field produced at the centre of the nucleus.

(iii) The magnetic moment associated with the electron.

The source of time varying magnetic field may be

(A) a permanent magnet

(B) an electric field changing linearly with time

(C) direct current

(D) a decelerating charge particle

(E) an antenna fed with a digital signal

Choose the correct answer from the options given below.

A wire$5 \mathrm{m}$long is supported horizontally at a height of $15 \mathrm{m}$ along east-west direction. When it is about to hit the ground, calculate the average e.m.f. induced in it. ($g=10 \mathrm{m} {\mathrm{s}}^{-2}$). The horizontal magnetic field is $B=3.6\times {10}^{-5} \mathrm{T}$

Two identical cell each of emf $5 \mathrm{V}$ is connected as shown in figure, then magnetic field at point P will be

A neutral particle of mass $28 \mathrm{g}$ is at rest in a uniform magnetic field $B=\frac{200}{3} \mathrm{T}$. At $t=0$, particle decays into two particles of equal mass, and one of them having charge $3\mu \mathrm{C}$. Both of them move in separate paths lying in the plane perpendicular to magnetic field $B$. At later time $t$, the two particles collide first time. (Neglect the interaction force). Then calculate $t$ in seconds

$\left(\text{Take} \pi =\frac{22}{7}\right)$

A uniform magnetic field exists in a circular region of radius $R=10 \mathrm{m}$. At time $t=0$, a conducting circular loop of radius $R=10 \mathrm{m}$ completely encloses the field. The circular loop starts moving in its plane and perpendicular to the magnetic field with a uniform velocity $v=5 \mathrm{m} {\mathrm{s}}^{-1}$. Intensity of magnetic field is $\mathrm{B}=20 \mathrm{mT}$. Find the induced emf (in volt) in the loop at time $t=2 \mathrm{s}$.(Take $\sqrt{3}=1.73$ )

A small current element $i\mathrm{d}\overrightarrow{\mathit{l}}$ with $\mathrm{d}\overrightarrow{l}=2\hat{\mathrm{k}} \mathrm{mm}$ and $I=2 \mathrm{A}$ is centred at the origin. The direction of the magnetic field at position $6 \mathrm{m}$ Westward from the origin will be

In the given figure at point $\mathrm{P}$. what is the direction of magnetic field.

An element $∆\overrightarrow{\mathrm{i}}=∆\mathrm{y}\hat{\mathrm{j}}$ is placed at the origin and carries current $\mathrm{i}$ then magnetic field at distance $0.2 \mathrm{m}$ on $+\mathrm{z}-$ axis will be pointing towards

A current carrying wire is along north-east direction and position vector $\left(\overrightarrow{\mathrm{r}}\right)$ is along outward to the plane of paper. Direction of magnetic field will be

How direction of magnetic field is identified? explain.

The magnetic field created at the nucleus by the revolving electron in the second excited state of $\mathrm{H}-$atom is $B$. The field created by the electron in the ground state in such an atom will be-

Direction of magnetic field at point $P,$ due to current carrying wire will be (two quarter circle lie in $xy$ and $yz$ plane centred at $P$)

Two long parallel wires $\mathrm{P}$ and $\mathrm{Q}$ are both perpendicular to the plane of the paper with distance of $5 \mathrm{m}$ between them. If $\mathrm{P}$ and $\mathrm{Q}$ carry current of $2.5$ amp and $5$ amp respectively in the same direction, then the magnetic field at a point half-way between the wires is

Which field is produced by a moving charge.

 Match List-I with List-II

List-I (Y vs X)		List-II (Shape of Graph)
(A)	Y = magnetic susceptibility X = magnetising field	(I)
(B)	Y = magnetic field X = distance from centre of a current carrying wire for x < a (where a=radius of wire)	(II)
(C)	Y = magnetic field X = distance from centre of a current carrying wire for x > a (where a = radius of wire)	(III)
(D)	Y= magnetic field inside solenoid X = distance from center	(IV)

Choose the correct answer from the options given below :

The magnetic field inside a solid conducting long wire at distance r from its axis is given as $B=B_0{r}^3$ where $B_0$ is constant. Which of the following relations correctly represents current enclosed in the loop of radius r shown in figure:

Pick out the wrong statements among the following:

What is the magnetic field at point $P$ if wire (infinite) is bent at $90^{\mathrm{o}}$ and current is flowing through it in opposite direction at point O: