An electric dipole of moment 4 × 10 - 10 cm is placed in a uniform electric field of intensity 10 × 10 6 V / m . Find its maximum and minimum potential energy.

U = - p E cos θ Where, p = dipole moment E = electric field θ = angle between dipole and electric field (I). When the angle between the dipole moment and electric field is 180° then the potential energy of electric dipole is maximum. U = - p E cos θ ⇒ U = - ( 4 × 10 - 10 ) × ( 10 × 10 6 ) cos 180 ⇒ U = - ( 4 × 10 - 3 ) × ( - 1 ) = 4 × 10 - 3 J (II). When the angle between the dipole moment and electric field is zero then the potential energy of electric dipole is minimum. U = - p E cos θ ⇒ U = - ( 4 × 10 - 10 ) × ( 10 × 10 6 ) cos 0 ⇒ U = - ( 4 × 10 - 3 ) × ( 1 ) = - 4 × 10 - 3 J

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12th West Bengal Board

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An alpha particle having $1$ Mev initial energy is moving directly towards a fixed uranium nucleus. Find the distance of nearest approach between them. Is the acceleration of the alpha particle constant during the time? Given, the atomic number of uranium is $92$ ; charge of an electron $e = 1.6 \times 10^{- 19} C$ alpha particle is the helium nucleus and it contains $2$ protons and $2$ neutrons.

Important Questions on Interaction of Charged Particles, Electric Field and Potential

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A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 2 - Interaction of Charged Particles, Electric Field and Potential>EXERCISE 2>Q 27

Electrons are released in the atmosphere due to collision between air molecules and cosmic ray particles. Such an electron is acted on by an electrostatic force due to electric field of

\vec{E}

of the earth. The electric field of the earth has magnitude

E = 110 V / m

and is directed downward. What is the change in the electric potential energy of a released electron when the electrostatic force moves it vertically upward through a height of

h = 50 m

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12th West Bengal Board

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A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 2 - Interaction of Charged Particles, Electric Field and Potential>EXERCISE 2>Q 28

Accurate measurements shows the earth has a negative charge and the corresponding intensity at the earth's surface is found to be equal to

110 V / m

. If the radius of the earth is

6400 km,

what is the magnitude of this charge?

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12th West Bengal Board

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A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 2 - Interaction of Charged Particles, Electric Field and Potential>EXERCISE 2>Q 29

At the eight corners of cube of side a are situated equal charges of q units each. What is potential at the center of cube at point O?

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12th West Bengal Board

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A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 2 - Interaction of Charged Particles, Electric Field and Potential>EXERCISE 2>Q 30

At the eight corners of cube of side a are situated equal charges of q units each.

(i) intensity

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A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 2 - Interaction of Charged Particles, Electric Field and Potential>EXERCISE 2>Q 31

Three charges

+ q

are kept fixed at the vertices of an equilateral triangle of side x. At time

t = 0

, they are released. Determine the total kinetic energy of the charges after a long (infinite time)

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12th West Bengal Board

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A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 2 - Interaction of Charged Particles, Electric Field and Potential>EXERCISE 2>Q 32

There is

10^{- 2}

Mole of water placed in an electric field of strength

10^{5} V / m

. Assuming that the dipole moment of all the molecules of water are aligned to the direction of electric field, find the work to be done to rotate the dipole moments of all molecules through

45 ° .

Given dipole moment of water molecule is

6.3 \times 10^{- 30} cm

And Avogadro number,

N_{A} = 6.023 \times 10^{23}

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12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 2 - Interaction of Charged Particles, Electric Field and Potential>EXERCISE 2>Q 33

An electric dipole of moment

4 \times 10^{- 10} cm

is placed in a uniform electric field of intensity

10 \times 10^{6} V / m .

Find its maximum and minimum potential energy.

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12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 2 - Interaction of Charged Particles, Electric Field and Potential>EXERCISE 2>Q 34

A small metal ball is suspended by means of a weightless string between the plates of a large plane capacitor. If the ball is charged to

+ q

and upper plate is charged positively, what will be the period of oscillation of such pendulum. (note : A capacitor is just two parallel plates of conducting material)

Important Questions on Interaction of Charged Particles, Electric Field and Potential

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