Electric Charges and Fields Test

Result

Electric Charges and Fields Test - 83

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Weekly Quiz Competition

Question 1
1 / -0

Three point charges $$q , 2 q$$ and 8$$q$$ are to be placed on a 9$$\mathrm { cm }$$ long straight line. Find the position where the charges should be placed such that the potential energy of this system is minimum. In this situation, what is the electric field at the position of the charge q due to the other two charges?

A
$$20 \mathrm { cm } , 24 \mathrm { N } / \mathrm { C }$$

B
$$12 \mathrm { cm } , 2 \mathrm { NC }$$

C
$$3 cm, zero$$

D
$$9 cm,zero$$

Solution
Question 2
1 / -0

A rod of length L has a total charge Q distributed uniformly along its length. It is bent in the shape of a semicircle The magnitude of the electric field at the centre of curvature of the semicicle is

A
$$\dfrac { Q }{ { 2\in }_{ o }{ L }^{ 2 } } $$

B
$$\dfrac { Q }{ { 4\in }_{ o }{ L }^{ 2 } } $$

C
$$\dfrac { Q }{ { 2\pi \in }_{ o }{ L }^{ 2 } } $$

D
$$\dfrac { Q }{ { 4\pi \in }_{ o }{ L }^{ 2 } } $$

Solution
Question 3
1 / -0

2 sphere with charge $$Q_1$$, $$Q_2$$ respectively with $$Q_1 \gg Q_2$$. The charges are d distance apart and radius of both sphere are same. The force they exert on one another is $$F_1$$. The spheres are made to touch one another and then separated to distance d apart. The force they exert on one another now is $$F_2$$. Then $${F_ 1 }/F_ 2 $$ is :-

A
$$4Q_ 1 /Q_ 2 $$

B
$$Q_ 1 /4Q_ 2 $$

C
$$4Q_ 2/Q_ 1 $$

D
$$Q_ 2/4Q_ 1 $$

Solution
Question 4
1 / -0

Two very small spheres A and B charged with $$+10$$ and $$+20$$ coulomb respectively and separated by a distance of $$80cm$$.The electric field at point on the line joining the centres of the two spheres will be zero at almost how much distance from A ?

A
$$20cm$$

B
$$33cm$$

C
$$45cm$$

D
$$60cm$$

Solution
Question 5
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Point charges $$+ 4 q , - q$$ and $$+ 4 q$$ are kept on the $$x$$ -axis at points $$x = 0 , x = a$$ and $$x = 2 a$$ respectively, then

A
Only $$q$$ is in stable equilibrium

B
None of the charges are in equilibrium

C
All the charges are in unstable equilibrium

D
All the charges are in stable equilibrium

Solution
Question 6
1 / -0

Choose the correct option that shows the rod and fur after charging

A

B

C

D
Question 7
1 / -0

Electrostatic field is

A
Conservative

B
Non conservative

C
Some where conservative and come where non conservative

D
none of these
Question 8
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A water particle of mass $$10.0mg$$ and having charge of $$1.50\times {10}^{-6}C$$ stays suspended in a room. What is the magnitude of electric field in the room ?what is its diection?

A
$$33.34 N/C$$, down ward

B
$$66.67 N/C$$, downward

C
$$33.34 N/C$$, upward

D
$$66.67 N/C$$, upward

Solution
Question 9
1 / -0

What is the percentage change in distance if the force of attraction between two point charges increases to $$4$$times keeping magnitude of charges constant?

A
Decreased to $$50%$$of initial value

B
Increased to $$50%$$ of intial value

C
Decreased to $$25%$$ of initial value

D
Increased to $$25%$$ of initial value

Solution
Question 10
1 / -0

Two charges each equal to $$2\mu C$$ are 0.5m apart. If both of them exist inside vacuum, then the force between them is

A
1.89 N

B
2.44 N

C
0.144 N

D
3.144 N

Solution