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Question (1)

QN0038795

A vertical electric field of magnitude just prevents a water droplet of a mass from falling. The value of charge on the droplet will be :
(Given )

(A)
(B)
(C)
(D)

Correct Answer: B

Explanation:

(b) As water droplet is at rest

So,

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Question (2)

QN0038796

A large nonconducting sheet is given a uniform charge density. Two uncharged small metal rods A and B are placed near the sheet as shown in figure. Then

(A)
attracts
(B)
attracts
(C)
A attracts B
(D)
All of these

Correct Answer: D

Explanation:

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Question (3)

QN0038797

A charged ball hangs from a silk thread , which makes an angle with a large charged conducting sheet , as shown in the figure. The surface charge density of the sheet is proportional to

(A)
(B)
(C)
(D)

Correct Answer: C

Explanation:

(c)

Dividing (i) by (ii),

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Question (4)

QN0038798

Two point charges and are separated by a certain distance. If then in between the charges the electric field is zero at a point

(A)
closer to
(B)
closer to
(C)
exactly at the mid-point of line segment joining and .
(D)
no where on the line segment joining and .

Correct Answer: B

Explanation:

Electric field is directly proportional to the magnitude of charge and inversely proportional to the square of the distance from the charge. Therefore charge produce a comparatively stronger electric field than which get at cancelled with each other at a point closer to .

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Question (5)

QN0038799

If an electron has an initial velocity in a direction different from that of an electric field, the path of the electron is

(A)
a straight line
(B)
a circle
(C)
an ellipse
(D)
a parabolà

Correct Answer: D

Explanation:

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Question (6)

QN0038800

In the figure, charge is placed at origin . When the charge is displaced from its position the electric field at point changes

(A)
at the same time when is displaced.
(B)
at a time after where is the speed of light.
(C)
at a time after
(D)
at a time after

Correct Answer: B

Explanation:

The electric field around a charge propagates with the speed of light away from the charge. Therefore the required time .

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Question (7)

QN0038801

The electric field intensity just sufficient to balance the earth's gravitational attraction on an electron will be: (given mass, charge of an electron respectively are and .)

(A)
(B)
(C)
(D)

Correct Answer: A

Explanation:

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Question (8)

QN0038802

is an equilateral triangle. Charges are placed at each corner as shown in fig. The electric intensity at centre will be

(A)
.
(B)
(C)
(D)
zero

Correct Answer: D

Explanation:

Unit positive charge at will be repelled equally by three charges at the three corners of triangle. By symmetry, resultant at would be zero.

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Question (9)

QN0038803

Two point charges and are located at and respectively. The point on axis at which net electric field is zero due to these charges is

(A)
(B)
(C)
(D)

Correct Answer: C

Explanation:

Let is the observation point at a distance from and at from .

Given now, net EFI at

(Electric Field Intensity) at due to

is at from origin

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Question (10)

QN0038804

A pendulum bob of mass carrying a charge is at rest with its string making an angle with the vertical in a uniform horizontal electric field . The tension in the string is

(A)
and
(B)
and
(C)
(D)

Correct Answer: B

Explanation:

In equilibrium,

From (1),

From (2),

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Question (1)

A vertical electric field of magnitude just prevents a water droplet of a mass from falling. The value of charge on the droplet will be :(Given )

Explanation:

Link:

Question (2)

A large nonconducting sheet is given a uniform charge density. Two uncharged small metal rods A and B are placed near the sheet as shown in figure. Then

Explanation:

Link:

Question (3)

A charged ball hangs from a silk thread , which makes an angle with a large charged conducting sheet , as shown in the figure. The surface charge density of the sheet is proportional to

Explanation:

Link:

Question (4)

Two point charges and are separated by a certain distance. If then in between the charges the electric field is zero at a point

Explanation:

Link:

Question (5)

If an electron has an initial velocity in a direction different from that of an electric field, the path of the electron is

Explanation:

Link:

Question (6)

In the figure, charge is placed at origin . When the charge is displaced from its position the electric field at point changes

Explanation:

Link:

Question (7)

The electric field intensity just sufficient to balance the earth's gravitational attraction on an electron will be: (given mass, charge of an electron respectively are and .)

Explanation:

Link:

Question (8)

is an equilateral triangle. Charges are placed at each corner as shown in fig. The electric intensity at centre will be

Explanation:

Link:

Question (9)

Two point charges and are located at and respectively. The point on axis at which net electric field is zero due to these charges is

Explanation:

Link:

Question (10)

A pendulum bob of mass carrying a charge is at rest with its string making an angle with the vertical in a uniform horizontal electric field . The tension in the string is

Explanation:

Link:

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A vertical electric field of magnitude just prevents a water droplet of a mass from falling. The value of charge on the droplet will be :
(Given )