Q: In which orientation is the potential energy of a dipole in a uniform electric field the greatest?

When $$\vec{p} is $$anti-parallel to $$\vec{E}$$ ($$\theta = 180^\circ)$$

Question 1

Which of the following statements about electric field lines is correct?

Accepted Answer

Electric field lines begin on positive charges and terminate on negative charges.

Question 2

A water molecule acts as an electric dipole because:

Accepted Answer

The chemical bonds cause a displacement of charge, resulting in a net negative charge on the oxygen end and a net positive charge on the hydrogen end.

Question 3

The electric dipole moment $$\vec{p} is $$defined as:

Accepted Answer

$$\vec{p} = q \vec{d}$$, directed from -q to +q

Question 4

Which property of electric field lines indicates the strength of the electric field?

Accepted Answer

The closeness of the field lines

Question 5

A dipole is placed in a uniform electric field. What is the net force on the dipole?

Accepted Answer

The net force is zero

Question 6

The torque $$	au$$ experienced by an electric dipole in a uniform electric field $$\vec{E} is $$given by:

Accepted Answer

$$	au = pE \sin 	heta$$

Question 7

The potential energy $$U of an $$electric dipole in a uniform electric field is:

Accepted Answer

$$U = -pE \cos 	heta$$

Question 8

In which orientation is the potential energy of a dipole in a uniform electric field the greatest?

Accepted Answer

When $$\vec{p} is $$anti-parallel to $$\vec{E}$$ ($$	heta = 180^\circ)$$

Question 9

Which of the following is a correct rule for drawing electric field lines?

Accepted Answer

The number of field lines is proportional to the magnitude of the charge.

Question 10

A real-world example of electric dipoles is found in:

Accepted Answer

Water molecules, which are excellent solvents due to their dipole nature

Question 11

If two equal and opposite charges are separated by a distance $$d$$, what is the magnitude of the electric dipole moment?

Accepted Answer

$$p = qd$$

Question 12

Which scenario best describes a stable equilibrium for a dipole in a uniform electric field?

Accepted Answer

The dipole moment $$\vec{p} is $$parallel to the electric field $$\vec{E}.$$

Question 13

Which equation correctly represents Coulomb’s Law for the force between two point charges $$q_1$$ and $$q_2$$ separated by distance $$r$$?

Accepted Answer

$$F = \frac{k_e q_1$ q_2$}{r^2$}$$

Question 14

Which of the following best describes the direction of the electric field at a point?

Accepted Answer

It is tangent to the electric field line at that point.

Question 15

A dipole in a uniform electric field experiences:

Accepted Answer

No net force but a torque.

Question 16

Which of the following is NOT a property of electric field lines?

Accepted Answer

They can form closed loops.

Question 17

In a real-life scenario, why does lightning occur during thunderstorms?

Accepted Answer

Because large electric fields build up between clouds and the ground, causing charge separation and discharge.

Question 18

If a dipole is rotated from a stable equilibrium position to an unstable equilibrium position in a uniform electric field, what happens to its potential energy?

Accepted Answer

It increases.

Question 19

Which equation gives the electric field $$E$$ due to a point charge $$q at a $$distance $$r$$?

Accepted Answer

$$E = \frac{k_e q}{r^2$}$$

Question 20

A dipole is placed in a uniform electric field at an angle $$	heta to $$the field. What is the expression for the torque on the dipole?

Accepted Answer

$$	au = pE \sin 	heta$$

Electric Charge and Electric Field: Study Notes for Physics with Calculus

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