Match List ‐ I (Experiment performed) with List ‐ II (Phenomena discovered/associated)and select the correct option from the options given below the lists List-I List-II ( a ) Davisson and Germer experiment i Wave nature of electrons b Millikan's oil drop experiment ii Charge of an electron c Rutherford experiment iii Quantisation of energy levels d Franck-Hertz experiment ( iv ) Existence of the nucleus

( a ) ‐ ( i ) , ( b ) ‐ ( ii ) , ( c ) ‐ ( iv ) , ( d ) ‐ ( iii )

( a ) ‐ ( iii ) , ( b ) ‐ ( iv ) , ( c ) ‐ ( i ) , ( d ) ‐ ( ii )

( a ) ‐ ( iv ) , ( b ) ‐ ( iii ) , ( c ) ‐ ( ii ) , ( d ) ‐ ( i )

( a ) ‐ ( i ) , ( b ) ‐ ( ii ) , ( c ) ‐ ( iii ) , ( d ) ‐ ( iv )

A uniform electric field, E → = - 400 3 j ^ N C - 1 is applied in a region. A charged particle of mass m carrying positive charge q is projected in this region with an initial speed of 2 10 × 10 6 m s - 1 . This particle is aimed to hit a target T , which is 5 m away from its entry point into the field as shown schematically in the figure. Take q m = 10 10 C kg - 1 . Then

time taken by the particle to hit T could be 5 6 μ s as well as 5 2 μ s

the particle will hit T if projected at an angle 45 ° from the horizontal

time taken by the particle to hit T is 5 3 μ s

EASY

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Which one of the following statements is true regarding electric field at a point?

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Important Questions on Electrostatics

EASY

Physics>Electricity and Magnetism>Electrostatics>Electric Field

A charged particle initially at rest at

O

, when released follows a trajectory as shown. Such a trajectory is possible in the presence of
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HARD

Physics>Electricity and Magnetism>Electrostatics>Electric Field

A thin disc of radius $b = 2 a$ has a concentric hole of radius $a$ in it (see figure). It carries uniform surface charge $σ$ on it. If the electric field on its axis at a height $h (h < < a)$ from its centre is given as $C h$ then the value of $C$ is

Question Image

EASY

Physics>Electricity and Magnetism>Electrostatics>Electric Field

The electric field in a certain region is acting radially outward and is given by

E = A r

. A charge contained in a sphere of radius

a

centred at the origin of the field will be given by

HARD

Physics>Electricity and Magnetism>Electrostatics>Electric Field

Two non-conducting solid spheres of radii $R$ and $2 R$ , having uniform volume charge densities $ρ_{1}$ and $ρ_{2}$ , respectively, touch each other. The net electric field at a distance $2 R$ from the centre of the smaller sphere, along the line joining the centres of the spheres, is zero. The ratio $\frac{ρ_{1}}{ρ_{2}}$ can be

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Field

A toy car with charge q moves on a frictionless horizontal plane surface under the influence of a uniform electric field

\vec{E}

. Due to the force

q \vec{E}

, its velocity increases from 0 to

6 m s^{- 1}

in one second duration. At that instant the direction of the field is reversed. The car continues to move for two more seconds under the influence of this field. The average velocity and the average speed of the toy car between

0

3

seconds are respectively

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Field

An electric field due to a positively charged long straight wire at a distance

r

from it is proportional to

r^{- 1}

in magnitude. Two electrons are orbiting such a long straight wire in circular orbits of radii

1 \overset{\circ}{A}

and

2 \overset{\circ}{A}

. The ratio of their respective time periods is

HARD

Physics>Electricity and Magnetism>Electrostatics>Electric Field

A wire of length

L = 20 c m

is bent into a semi-circular arc and the two equal halves of the arc are uniformly charged with charges

+ Q

and

- Q

as shown in the figure. The magnitude of the charge on each half is

|Q| = 10^{3} ε_{0}

, where

ε_{0}

is the permittivity of free the space. The net electric field at the centre

O

EASY

Physics>Electricity and Magnetism>Electrostatics>Electric Field

A hollow metal sphere of radius

R

is uniformly charged. The electric field due to the sphere at a distance

r

from the center

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Field

A metallic sphere is placed in a uniform electric field. The line of force follow the path(s) shown in the figure as,

Question Image

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Field

For a uniformly charged ring of radius

R,

the electric field on its axis has the largest magnitude at a distance

h

from its centre. Then value of

h

is:

EASY

Physics>Electricity and Magnetism>Electrostatics>Electric Field

Match List $‐ I$ (Experiment performed) with List $‐ II$ (Phenomena discovered/associated)and select the correct option from the options given below the lists

	List-I		List-II
$(a)$	Davisson and Germer experiment	$(i)$	Wave nature of electrons
$(b)$	Millikan's oil drop experiment	$(ii)$	Charge of an electron
$(c)$	Rutherford experiment	$(iii)$	Quantisation of energy levels
$(d)$	Franck-Hertz experiment	$(iv)$	Existence of the nucleus

HARD

Physics>Electricity and Magnetism>Electrostatics>Electric Field

A uniform electric field, $\vec{E} = - 400 \sqrt{3} \hat{j} N C^{- 1}$ is applied in a region. A charged particle of mass $m$ carrying positive charge $q$ is projected in this region with an initial speed of $2 \sqrt{10} \times 10^{6} m s^{- 1}$ . This particle is aimed to hit a target $T$ , which is $5 m$ away from its entry point into the field as shown schematically in the figure. Take $\frac{q}{m} = 10^{10} C {kg}^{- 1}$ . Then

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MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Field

Charges Q, 2Q and 4Q are uniformly distributed in three dielectric solid spheres 1, 2 and 3 of radii R/2, R and 2R respectively, as shown in the figure. If magnitudes of the electric fields at point P at a distance R from the centre of spheres 1, 2 and 3 are

E_{1}, E_{2}

and

E_{3}

respectively, then

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MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Field

A total charge

q

is divide as

q_{1}

and

q_{2}

which are kept at two of the vertices of an equilateral triangle of side

a

. The magnitude of the electric field E at the third vertex of the triangle is to be depicted schematically as a function of

x = \frac{q_{1}}{q}

. Choose the correct figure.

EASY

Physics>Electricity and Magnetism>Electrostatics>Electric Field

The bob of a simple pendulum has mass

2 g

and a charge of

5.0 μ C .

It is at rest in a uniform horizontal electric field of intensity

2000 V / m

At equilibrium, the angle that the pendulum makes with the vertical is:

(t a k e g = 10 m / s^{2})

HARD

Physics>Electricity and Magnetism>Electrostatics>Electric Field

Four point charges

- q, + q, + q

and

- q

are placed on y-axis at

y = - 2 d, y = - d,

and

y = + 2 d,

respectively. The magnitude of the electric field

E

at a point on the x-axis at

x = D,

with

D ≫ d,

will behave as:

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Field

Two parallel infinite line charges with linear charge densities

+ λ C m^{- 1}

and

- λ C m^{- 1}

are placed at a distance of

2 R

in free space. What is the electric field mid-way between the two-line charges?

MEDIUM

Physics>Electricity and Magnetism>Electrostatics>Electric Field

Two point charges

q_{1} (\sqrt{10} μC)

and

q_{2} (- 25 μC)

are placed on the

x

-axis at

x = 1 m

and

x = 4 m

respectively. The electric field

(in V m^{- 1})

at a point

y = 3 m

y

-axis is,

[Take \frac{1}{4 π ϵ_{0}} = 9 \times 10^{9} N m^{2} C^{- 2}]

HARD

Physics>Electricity and Magnetism>Electrostatics>Electric Field

An electron falls from rest through a vertical distance

h

in a uniform and vertically upward directed electric field

E

. The direction of electric filed is now reversed, keeping its magnitude the same. A proton is allowed to fall from rest in it through the same vertical distance

h

. The time of fall of the electron, in comparison to the time of fall of the proton is

HARD

Physics>Electricity and Magnetism>Electrostatics>Electric Field

The figures below depict two situations in which two infinitely long static line charges of constant positive line charge density

λ

are kept parallel to each other. In their resulting electric field, point charges

q

and

- q

are kept in equilibrium between them. The point charges are confined to move in the

x

direction only. If they are given a small displacement about their equilibrium positions, then the correct statements(s) is (are)

Question Image

Which one of the following statements is true regarding electric field at a point?

Important Questions on Electrostatics

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