Q: An electron is accelerated from rest across a potential difference of $$100,000\ \text{V}. $$What is the change in its electric potential energy? ($$q = -1.6 \times 10$$^{-19}$$\ \text{C})$$

$$-1.6 \times 10$$^{-14}$$\ \text{J}$$

Q: A Van de Graaff generator accelerates an electron from rest across a $$+100,000\ \text{V}$$ potential difference. What is the final speed of the electron? ($$m_e = 9.11 \times 10$$^{-31}$$\ \text{kg}$$, $$q = 1.6 \times 10$$^{-19}$$\ \text{C}$$, neglect relativity)

$$1.87 \times 10^8$\ \text{m/s}$$

Q: If the electric potential difference between two points is $$\Delta V = 3.0\ \text{V}$$ and the electric field between them is $$2.0 \times 10^2$\ \text{V/m}$$, what is the spacing between the points?

$$1.5 \times 10$$^{-2}$$\ \text{m}$$

Q: What is the value of $$1\ \text{eV} in $$joules?

$$1.60 \times 10$$^{-19}$$\ \text{J}$$

Question 1

Which of the following best defines the electric potential at a point in space?

Accepted Answer

The electric potential energy per unit charge at that point.

Question 2

What is the SI unit of electric potential?

Accepted Answer

Volt (V)

Question 3

An electron is accelerated from rest across a potential difference of $$100,000\ 	ext{V}. $$What is the change in its electric potential energy? ($$q = -1.6 	imes 10$$^{-19}$$\ 	ext{C})$$

Accepted Answer

$$-1.6 	imes 10$$^{-14}$$\ 	ext{J}$$

Question 4

Which equation correctly relates the electric field $$E$$ and the electric potential difference $$\Delta V$$ for a uniform field?

Accepted Answer

$$E = -\frac{\Delta V}{\Delta s}$$

Question 5

A parallel-plate capacitor has a charge of $$4.0\ 	ext{nC} on $$each plate, an area of $$0.01\ 	ext{m}^2$$, and a separation of $$1.0\ 	ext{mm}. $$What is the potential difference between the plates? ($$\$$epsilon_0$$ = 8.85 	imes 10$$^{-12}$$\ 	ext{C}^2/	ext{N}\cdot	ext{m}^2)$$

Accepted Answer

$$-45\ 	ext{V}$$

Question 6

What is the electric potential at a distance $$r$$ from a point charge $$q$$?

Accepted Answer

$$V = \frac{kq}{r}$$

Question 7

A $$4.0 	imes 10$$^{-9}$$\ 	ext{C}$$ point charge is placed at the origin. What is the electric potential at a point $$1.2\ 	ext{m}$$ away? ($$k = 8.99 	imes 10^9$\ 	ext{N}\cdot	ext{m}^2/	ext{C}^2)$$

Accepted Answer

$$+30\ 	ext{V}$$

Question 8

If two point charges, $$+2q$$ and $$-q$$, are fixed in place, how many points along the line joining them have zero electric potential?

Accepted Answer

Two

Question 9

Which of the following statements about equipotential surfaces is correct?

Accepted Answer

The electric field is always perpendicular to equipotential surfaces.

Question 10

A Van de Graaff generator accelerates an electron from rest across a $$+100,000\ 	ext{V}$$ potential difference. What is the final speed of the electron? ($$m_e = 9.11 	imes 10$$^{-31}$$\ 	ext{kg}$$, $$q = 1.6 	imes 10$$^{-19}$$\ 	ext{C}$$, neglect relativity)

Accepted Answer

$$1.87 	imes 10^8$\ 	ext{m/s}$$

Question 11

Which of the following is true about the work done by the electric field when moving a charge along an equipotential surface?

Accepted Answer

The work done is zero.

Question 12

If the electric potential difference between two points is $$\Delta V = 3.0\ 	ext{V}$$ and the electric field between them is $$2.0 	imes 10^2$\ 	ext{V/m}$$, what is the spacing between the points?

Accepted Answer

$$1.5 	imes 10$$^{-2}$$\ 	ext{m}$$

Question 13

Which of the following best describes the relationship between electric field lines and equipotential surfaces for a point charge?

Accepted Answer

Field lines are everywhere perpendicular to equipotential surfaces.

Question 14

A test charge $$q_0 is $$moved from point A to point B in a uniform electric field $$E$$ over a distance $$d. $$What is the work done by the field?

Accepted Answer

$$W_{AB} = q_0$ E d$$

Question 15

Which of the following is a correct expression for the total energy of an object including electric potential energy?

Accepted Answer

$$E = \frac{1}{2}mv^2$ + \frac{1}{2}I\$$omega^2$$ + mgh + \frac{1}{2}kx^2$ + 	ext{EPE}$$

Question 16

What is the value of $$1\ 	ext{eV} in $$joules?

Accepted Answer

$$1.60 	imes 10$$^{-19}$$\ 	ext{J}$$

Question 17

If the electric potential at point A due to a charge is $$+240\ 	ext{V}$$ and at point B is $$0\ 	ext{V}$$, what is the potential difference $$V_{BA}$$?

Accepted Answer

$$-240\ 	ext{V}$$

Question 18

Which of the following is true for conductors in electrostatic equilibrium?

Accepted Answer

They are always equipotential surfaces.

Electric Potential: Concepts, Calculations, and Applications

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