Electric Charges and Fields Test

Result

Electric Charges and Fields Test - 85

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Weekly Quiz Competition

Question 1
1 / -0

The electric field at (30, 30) cm due to a charge of _8 nC at the origin in $${ NC }^{ -1 }$$ is

A
$$-400\left( \overline { i } +\overline { j } \right)$$

B
$$400\left( \overline { i } +\overline { j } \right)$$

C
$$-200\sqrt { 2 } \left( \overline { i } +\overline { j } \right)$$

D
$$200\sqrt { 2 } \left( \overline { i } +\overline { j } \right)$$

Solution
Question 2
1 / -0

The force of repulsion between two points charges is $$F$$ , when these are $$1 m$$ apart. Now the point charges are replaced by conducting spheres of radii $$5 cm$$ having the charge same as that of point charges. The distance between their centers is $$1 m$$, then the force of repulsion will:-

A
increase

B
decrease

C
remain same

D
become $$\frac { 10 \mathrm { F } } { 9 }$$

Solution
Question 3
1 / -0

Two infinite linear charge are placed parallel at 0.1 m apart. It has density of 5 $$\mu$$ C/m,then the force per unit length of one of linear charges in N/m is;

A
2.5

B
3.25

C
4.5

D
7.5
Question 4
1 / -0

An infinite number of charges, each of charge $$1 \mu C ,$$ are placed on the $$x$$ -axis with co-ordinates $$x = 1,2,4,8 , \ldots \infty$$ a charge of 1$$C$$ is kept at the origin, then what is the net force acting on 1$$\mathrm { C }$$ charge

A
$$9000N$$

B
$$12000N$$

C
$$24000N$$

D
$$36000N$$

Solution
Question 5
1 / -0

For two infinitely long charge parallel sheets, the electric field at $$P$$ will be

A
$$\dfrac {\sigma}{2 x} - \dfrac {\sigma}{2 (r - x)}$$

B
$$\dfrac {\sigma}{2 r_{0}x} + \dfrac {\sigma}{2 \pi (r - x) \epsilon_{0}}$$

C
$$\dfrac {\sigma}{\varepsilon_{0}}$$

D
Zero

Solution
Question 6
1 / -0

Point charges $$+q,\ +q$$ and $$-q$$ are placed at the corners $$A,\ B$$ and $$C$$ respectively of an equilateral triangle $$ABC$$. The resultant force on $$-q$$ placed at $$C$$ acts

A
in a direction along the angle bisector of $$\angle$$$$ABC$$

B
in a direction making an angle of $$60^{o}$$ with $$BC$$

C
along $$BC$$

D
along $$AC$$
Question 7
1 / -0

There are Two charges +1 micro coulombs and +5 micrcoulombs. The ratio of the force acting on them will be

A
1 : 5

B
1 : 1

C
5 : 1

D
1 : 25

Solution
Question 8
1 / -0

A charge q is located at the center of a cube . The electric flux through any face is

A
$$\dfrac { \pi q }{ 6(4\pi \epsilon _{ 0 }) } $$

B
$$\dfrac { q }{ 6(4\pi \epsilon _{ 0 }) } $$

C
$$\dfrac { 2\pi q }{ 6(4\pi \epsilon _{ 0 }) } $$

D
$$\dfrac { 4\pi q }{ 6(4\pi \epsilon _{ 0 }) } $$

Solution
Question 9
1 / -0

The force between two electrons when placed in air is equal to 0.5 times the weight of an electron find the distance between two electrons (mass is electron= $$9.1\times 10^{-31}kg)$$

A
7.2 m

B
72 cm

C
72 m

D
720 m

Solution
Question 10
1 / -0

Electric and magnetic field are directed as $${ E }_{ 0 }\hat { i } $$ and $${ B }_{ 0 }\hat { k } $$, a particle of mass m and charge +q is released from position $$(0, 2, 0)$$ from rest. The velocity of that particle at $$(x, 5, 0)$$ is $$\left( 5\hat { i } +12\hat { j } \right) $$ the value of x will be

A
$$\dfrac { 169m }{ 2q{ E }_{ 0 } } $$

B
$$\dfrac { 25m }{ 2q{ E }_{ 0 } } $$

C
$$\dfrac { 25m }{ 12q{ E }_{ 0 } } $$

D
$$\dfrac { 144m }{ 12q{ E }_{ 0 } } $$

Solution