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Magnetic Effect Of Current And Magnetism

192 Questions Start Allen Test
All Exams Allen
Q26 Allen 2. AMPERE'S LAW MCQ
In a current carrying long solenoid the field produced does not depend on :-
A.
number of turns per unit length
B.
current in solenoid
C.
radius of cross section of the solenoid
D.
all of the above
Q27 Allen 2. AMPERE'S LAW MCQ
If length and number of turns becomes half for a solenoid then value of magnetic field becomes:-
A.
twice
B.
same
C.
half
D.
one fourth
Q28 Allen 2. AMPERE'S LAW MCQ
If number of turns and current become double for any solenoid, then value of magnetic field becomes :-
A.
twice
B.
same
C.
half
D.
four times
Q29 Allen 2. AMPERE'S LAW MCQ
A current of $1/4\pi$ ampere is flowing through a toroid. It has 1000 number of turn per meter then value of magnetic field (in Wb/m $^{2}$ ) along its axis is :-
A.
$10^{-2}$
B.
$10^{-3}$
C.
$10^{-4}$
D.
$10^{-7}$
Q30 Allen 2. AMPERE'S LAW MCQ
Mean radius of a toroid is 10 cm and number of turns are 500. If current flowing through it is 0.1 ampere then value of magnetic field (in tesla) for toroid :-
A.
$10^{-2}$
B.
$10^{-5}$
C.
$10^{-3}$
D.
$10^{-4}$
Q31 Allen 2. AMPERE'S LAW MCQ
A long solenoid has length L, average diameter D and n layer of turns. Each layer contains N turns. If current flowing through the solenoid is i the value of magnetic field at the centre :-
A.
Proportional to D
B.
Inversely proportional to D
C.
Does not depend on D
D.
Proportional to L
Q32 Allen 2. AMPERE'S LAW MCQ
A long solenoid carrying a current produces a magnetic field B along its axis. If the current is doubled and the number of turns per cm is halved, the new value of the magnetic field is:
A.
B/2
B.
B
C.
2B
D.
4B
Q33 Allen 2. AMPERE'S LAW MCQ
A long solenoid having 200 turns/cm and carries current i. Magnetic field at its axis is $6 \cdot 28 \times 10^{-2} \mathrm{~wb} / \mathrm{m}^2$ . An another solenoid having 100 turns/cm and carries $\frac{\mathrm{i}}{3}$ current, then magnetic field at its axis will be :-
A.
$1.05 \times 10^{-4} \mathrm{~Wb} / \mathrm{m}^2$
B.
$1.05 \times 10^{-2} \mathrm{~Wb} / \mathrm{m}^2$
C.
$1.05 \times 10^{-5} \mathrm{~Wb} / \mathrm{m}^2$
D.
$1.05 \times 10^{-3} \mathrm{~Wb} / \mathrm{m}^2$
Q34 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
A proton and an alpha particle are separately projected in a region where a uniform magnetic field exists. The initial velocities are perpendicular to the direction of magnetic field. If both the particles move along circles of equal radii, the ratio of momentum of proton to alpha particle $\left(\frac{P_{p}}{P_{\alpha}}\right)$ is :-
A.
1
B.
1/2
C.
2
D.
1/4
Q35 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
Cathode rays are moving between the poles of a magnet. Due to the effect of magnetic field of magnet :-
A.
velocity of rays increases
B.
velocity of rays decreases
C.
rays deflected towards south pole
D.
rays deflected in upward direction and perpendicular to the plane of the paper
Q36 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
Following charge has maximum frequency of rotation in uniform transverse magnetic field :
A.
a proton
B.
an alpha particle
C.
an electron
D.
a neutron
Q37 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
Which of the following particle will experiences maximum magnetic force, when projected with the same velocity perpendicular to a magnetic field :-
A.
electron
B.
proton
C.
$\mathrm{He^{+}}$
D.
$\mathrm{Li^{++}}$
Q38 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
When $\alpha$ and $\beta$ rays are subjected to a magnetic field which is perpendicular to the direction of their motion, with their same speed. The curvature of path of both the particles are :-
A.
equal
B.
more for $\alpha$ particles
C.
more for $\beta$ particles
D.
none
Q39 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
Two identically charged particles A and B initially at rest, are accelerated by a common potential difference V. They enters into a uniform transverse magnetic field B and describe a circular path of radii $r_{1}$ and $r_{2}$ respectively then their mass ratio is :-
A.
$\left(\frac{r_{1}}{r_{2}}\right)^{2}$
B.
$\left(\frac{r_{2}}{r_{1}}\right)^{2}$
C.
$\left(\frac{r_{1}}{r_{2}}\right)$
D.
$\left(\frac{r_{2}}{r_{1}}\right)$
Q40 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
An $\alpha$ -particle experiences a force of $3.84 \times 10^{-14} \mathrm{~N}$ when it moves perpendicular to magnetic field of $0.2 \mathrm{~Wb} / \mathrm{m}^2$ then speed of the $\alpha$ -particle is:
A.
$6.0 \times 10^{5} \mathrm{~m} / \mathrm{sec}$
B.
$5.0 \times 10^{5} \mathrm{~m} / \mathrm{sec}$
C.
$1.2 \times 10^{6} \mathrm{~m} / \mathrm{sec}$
D.
$3.8 \times 10^{6} \mathrm{~m} / \mathrm{sec}$
Q41 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
If an electron enters a magnetic field with its velocity pointing in the same direction as the magnetic field then:-
A.
the electron will turn towards right
B.
the electron will turn towards left
C.
the velocity of the electron will increase
D.
the velocity of the electron will increase
Q42 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
A charge having q/m equal to $10^{8}$ C/kg and with velocity $3 \times 10^{5}$ m/s enters into a uniform magnetic field B = 0.3T at an angle $30^{\circ}$ with direction of field. Then radius will be :-
A.
0.01 cm
B.
0.5 cm
C.
1 cm
D.
2 cm
Q43 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
When a charged particle enters in a uniform magnetic field its kinetic energy:-
A.
remains constant
B.
increases
C.
decreases
D.
becomes zero
Q44 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
Two particles x and y have equal charges and possessing equal kinetic energy enter in a uniform magnetic field and describe circular path of radius of curvature $r_{1}$ and $r_{2}$ respectively. The ratio of their masses is:
A.
$\left(\frac{r_{1}}{r_{2}}\right)$
B.
$\left(\frac{r_{1}}{r_{2}}\right)^{1/2}$
C.
$\left(\frac{r_{1}}{r_{2}}\right)^{2}$
D.
$\left(\frac{r_{2}}{r_{1}}\right)$
Q45 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
An electron having mass 'm' and kinetic energy E enter in uniform magnetic field B perpendicularly, then its frequency of uniform circular motion will be :-
A.
$\frac{\mathrm{eE}}{\mathrm{qVB}}$
B.
$\frac{2\pi\mathrm{m}}{\mathrm{eB}}$
C.
$\frac{\mathrm{eB}}{2\pi\mathrm{m}}$
D.
$\frac{2\mathrm{m}}{\mathrm{eBE}}$
Q46 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
In a mass spectrograph an ion A of mass number 24 and charge +e and an ion B of mass number 22 and charge +2e are entered in transverse magnetic field with same velocity. The ratio of radii of their paths respectively:-
A.
$\frac{11}{24}$
B.
$\frac{12}{11}$
C.
$\frac{11}{22}$
D.
$\frac{24}{11}$
Q47 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
A charge particle is moving in the direction of a magnetic field. The magnetic force acting on the particle :-
A.
is in the direction of its velocity
B.
is in the direction opposite to its velocity
C.
is perpendicular to its velocity
D.
is zero
Q48 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
An electron of kinetic energy of $7.2 \times 10^{-18}$ J is revolving in a circular path in magnetic field $9 \times 10^{-5}$ Wb/m $^{2}$ then radius of its circular path is:-
A.
1.25 cm.
B.
2.5 m.
C.
2.5 cm.
D.
25.0 cm.
Q49 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
An electron moves with velocity v in uniform transverse magnetic field B on circular path of radius 'r', then e/m for it is :-
A.
$\frac{\mathrm{v}}{\mathrm{Br}}$
B.
$\frac{\mathrm{B}}{\mathrm{rv}}$
C.
Bvr
D.
$\frac{\mathrm{vr}}{\mathrm{B}}$
Q50 Allen 3. MAGNETIC FORCE & MOVING CHARGE IN MAGNETIC FIELD MCQ
A proton, deutron and an $\alpha$ -particle are accelerated by same potential, enter in uniform magnetic field perpendicularly. Ratio of radii of circular path respectively:-
A.
$1:\sqrt{2}:\sqrt{2}$
B.
$2:2:1$
C.
$1:2:1$
D.
$1:1:1$