Question 1

A particle with charge $$q is $$moved from point A to point B in a uniform electric field $$\vec{E}. $$Which of the following correctly describes the work $$W$$ done by the electric field on the particle?

Accepted Answer

$$W = q \int_A^B \vec{E} \cdot d\vec{l}$$

Question 2

Two particles with masses $$m_1$$ and $$m_2$$ ($$m_2$$ \u003e $$m_1) $$and equal positive charges $$q$$ are released from rest in a uniform electric field. How do their accelerations compare?

Accepted Answer

The particle with smaller mass has greater acceleration.

Question 3

A dipole is placed in a uniform electric field and allowed to rotate. When is its electric potential energy minimized?

Accepted Answer

When the dipole is aligned with the electric field.

Question 4

Which of the following statements about equipotential surfaces is correct?

Accepted Answer

Equipotential surfaces are always perpendicular to electric field lines.

Question 5

The electrostatic work done on a charged particle as it moves from point A to point B in an electric field depends on:

Accepted Answer

Only the starting and ending points.

Question 6

A thin rod of length $$l$$ carries a uniformly distributed charge $$q. $$What is the expression for the potential $$V_P at a $$point $$P a $$distance $$d$$ from one end of the rod along a line perpendicular to the rod?

Accepted Answer

$$V_P = \frac{q}{4\pi\$$epsilon_0$$ l} \ln\left(\frac{l + \sqrt{l^2$ + d^2$}}{d}\right)$$

Question 7

If the electrostatic work done on a charged particle as it moves around a closed path is zero, what can you conclude about the work done along a segment of that path?

Accepted Answer

It may be nonzero.

Question 8

The potential difference $$V_{AB}$$ between two points A and B in the electric field of a point charge $$q_1 is $$given by:

Accepted Answer

$$V_{AB} = \frac{q_1$}{4\pi\$$epsilon_0$$} \left( \frac{1}{r_B} - \frac{1}{r_A} \right)$$

Question 9

A solid spherical conductor is given a net nonzero charge. The electrostatic potential of the conductor is:

Accepted Answer

Constant throughout the volume.

Question 10

Two metallic spheres, A (charged) and B (neutral), are connected by a wire. After equilibrium is reached, what happens to the electric potential energy of the system?

Accepted Answer

It decreases because the charges spread out, increasing their separation.

Question 11

The electric field $$\vec{E}$$ can be obtained from the potential $$V by$$:

Accepted Answer

$$\vec{E} = -
abla V$$

Question 12

A test charge $$+q is $$brought to point A, a distance $$r$$ from a charge $$+Q. $$Then a test charge $$+2q is $$brought to point B, a distance $$2r$$ from $$+Q. $$Compared to the electrostatic potential energy at A, the potential energy at B is:

Accepted Answer

The same

Question 13

In a uniform electric field $$E$$ between two parallel plates separated by distance $$d$$, what is the potential difference between the plates?

Accepted Answer

$$V = Ed$$

Question 14

Which of the following is true about the potential difference around a closed path in an electrostatic field?

Accepted Answer

It is always zero.

Question 15

A positive charge is moved from a region of higher potential to a region of lower potential. What can be said about the work done by the electric field?

Accepted Answer

The electric field does positive work.

Question 16

The potential at a distance $$r$$ from a point charge $$q ($$with zero potential at infinity) is:

Accepted Answer

$$V = \frac{1}{4\pi\$$epsilon_0$$} \frac{q}{r}$$

Question 17

Which reference position is commonly used to assign a unique value of electrostatic potential for (a) a system of charged particles and (b) an electric circuit?

Accepted Answer

The electric ground for the circuit and infinity for the system of charged particles.

Question 18

In an electric field, how does the electrostatic potential vary along a given field line?

Accepted Answer

It decreases in the direction of the electric field.

Question 19

An electron is pushed into an electric field from infinity and acquires a 1-V electrical potential. If two electrons are pushed the same distance into the same field, the electrical potential of the two electrons is:

Accepted Answer

1 V

Work and Energy in Electrostatics: Structured Study Notes

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