Moving Charges and Magnetism Test

Result

Moving Charges and Magnetism Test - 61

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

The force experienced by a pole of strength $$100$$ Am at a distance of $$0.2$$ m from a short magnet of length $$5 m$$ and pole strength of $$200$$ Am on its axial line will be:-

A
$$2.5 \times^{-2} N$$

B
$$2.5 N$$

C
$$5.0 \times^{-2} N$$

D
$$5.0 N$$

Solution
Question 2
1 / -0

Following figure shows the path of an electron that passes through two regions containing uniform magnetic fields of magnitudes $$B_1$$ and $$B_2$$. Its path in each region is a half circle,choose the correct option

A
$$B_1$$ is in to the page and it is stronger than $$B_2$$

B
$$B_1$$ is in to the page and it is weaker than $$B_2$$

C
$$B_1$$ is out of the page and it is weaker than $$B_2$$

D
$$B_1$$ is out of the page and it is stronger than $$B_2$$

Solution

Equating centripetal force with magnetic force,
$$\dfrac{mv^2}r = qvB$$
$$r = \dfrac{mv}{qB}$$
Thus path having greater r will have lower magnetic field. Therefore field $$B_1$$ is stronger.
Considering the right hand thumb rule, the direction of the magnetic field for region of magnetic field $$B_1$$ is into the page and where for region $$B_2$$ is out of the page.
Question 3
1 / -0

$$AB$$ and $$CD$$ are long straight conductor, distance $$d$$ apart, carrying a current $$I$$. The magnetic field at the midpoint of $$BC$$ is

A
$$\dfrac{{ - {\mu _0}I}}{{2\pi d}}\hat k$$

B
$$\dfrac{{ - {\mu _0}I}}{{\pi d}}\hat k$$

C
$$\dfrac{{ - {\mu _0}I}}{{4\pi d}}\hat k$$

D
$$\dfrac{{ - {\mu _0}I}}{{8\pi d}}\hat k$$

Solution

The field at the midpoint of $$BC$$ due to $$AB$$ is $$\left(-\dfrac{\mu_{0}}{4\pi}.\dfrac{i}{d/2}\hat{k}\right)$$ and the same is due to $$CD$$.

Therefore the total field is $$\left[-\left(\dfrac{\mu_{0}i}{\pi d}\right)\hat{k}\right]$$
Question 4
1 / -0

A magnetic filed:

A
Always exerts a force on charged particle

B
Never exerts a force on charged particle

C
Exerts a force, if the charged particle is moving across the magnetic field line

D
Exerts a force, if the charged particle is moving along the magnetic field line

Solution
Question 5
1 / -0

Magnetic field due to a horseshoe magnet is parallel to the plane of the paper and North Pole is on the left. Direct current in a straight wire is perpendicular to the plane of the paper, toward the observer. The wire will be deflected

A
downward

B
upward

C
on the right

D
first upward then downward

Solution

Magnetic field due to horse shoe magnet is parallel to the plane of the paper and North pole is on the left.
The wire will be deflected on the right due to I and moving wire will be $$180°$$ to each other.
Question 6
1 / -0

An electron has velocity v=$$\left( {2.0\times{{10}^6}\;m/s} \right)\hat{i} + \left( {3.0\times{{10}^{6\;}}m/s} \right)\hat{j}$$, magnetic field present is region is $$B\left( {0.030\;T} \right)\;i - \left( {0.15\;T} \right)j$$. Find the force on electron.

A
$$-6.24\times{10}^{-14} \hat{k}$$

B
$$-0.624\times{10}^{-14} \hat{k}$$

C
$$-62.4\times{10}^{-14} \hat{k}$$

D
$$-624\times{10}^{-14} \hat{k}$$

Solution
Question 7
1 / -0

A long straight wire along the z-axis carries a current I in the negative z direction. The magnetic vector field $$\overline {B}$$ at a point having coordinates (x, y) in the z=0 plane is :

A
$$\dfrac{\mu_0I(y\hat{i} - x \hat{j})}{2\pi (x^2+y^2)}$$

B
$$\dfrac{\mu_0I(x\hat{i} - y \hat{j})}{2\pi (x^2+y^2)}$$

C
$$\dfrac{\mu_0I(x\hat{j} - y \hat{i})}{4\pi (x^2+y^2)}$$

D
$$\dfrac{\mu_0I(x\hat{i} - y \hat{j})}{4\pi (x^2+y^2)}$$

Solution

An infinite wire carrying current in $$(-z)$$ axis
we have $$\vec { l } =\left( -\hat { k } \right) $$ (current vector)
$$\vec { l } =x\hat { i } +y\hat { j } \Rightarrow { r }^{ 2 }={ x }^{ 2 }+{ y }^{ 2 }$$
using Biot-Savart law fo rinfinite wire
$$\vec { B } =\cfrac { { \mu }_{ 0 }I }{ 2\pi r } \left( \cfrac { \vec { l } \times \vec { r } }{ r } \right) $$ ($$\cfrac { \vec { l } \times \vec { r } }{ r } $$ is the unit vector along $$\vec { B } $$)
$$=\cfrac { { \mu }_{ 0 }I }{ 2\pi { r }^{ 2 } } \left[ \left( -\hat { k } \right) \times \left( x\hat { i } +y\hat { j } \right) \right] \Rightarrow \vec { B } =\cfrac { { \mu }_{ 0 }I }{ 2\pi ({ x }^{ 2 }+{ y }^{ 2 }) } \left( y\hat { i } -x\hat { j } \right) $$ (Ans)
Question 8
1 / -0

Two free parallel straight wires carrying currents in opposite direction

A
attract each other

B
do not affect each other

C
repel each other

D
get rotated to be perpendicular to the each other

Solution

Two wires, if carries current in opposite direction, they repel each other.
Question 9
1 / -0

In the given region, magnetic field is applied in the direction perpendicular to the plane of paper and outward. If the charge particle goes undeflected, then the direction electric field present in the region is-

A
Upwards on the paper

B
Downwards on the paper

C
Rightwards on the paper

D
Leftwards on the paper
Question 10
1 / -0

A charged particle moving in a magnetic field experience maximum magnetic force when

A
it moves parallel to the field

B
it moves in opposite direction of the field

C
it moves at right angles to the direction of field

D
it moves at an angle $$45^0$$ to the direction of field

Solution