Q: A proton is placed in a uniform electric field of magnitude $$150\ \mathrm{N/C}$$, created by a negatively charged plate, at a distance of $$1.0\ \mathrm{m}$$ from the plate. What is the electric potential energy of the proton relative to the plate?

$$U = 2.4 \times 10$$^{-17}$$\ \mathrm{J}$$

Q: Given the formula for electric potential energy in a uniform electric field, $$U = q|\vec{E}|y$$, what is the potential energy of an electron ($$q = -1.6 \times 10$$^{-19}$$\ \mathrm{C}) $$located $$1.0\ \mathrm{m}$$ from a negatively charged plate in a field of $$150\ \mathrm{N/C}$$?

$$U = -2.4 \times 10$$^{-17}$$\ \mathrm{J}$$

Q: If a proton is released from rest and moves $$1.0\ \mathrm{m} in a $$uniform electric field of $$150\ \mathrm{N/C}$$, what is the change in its electric potential energy?

$$\Delta U = 2.4 \times 10$$^{-17}$$\ \mathrm{J}$$

Question 1

A proton is placed in a uniform electric field of magnitude $$150\ \mathrm{N/C}$$, created by a negatively charged plate, at a distance of $$1.0\ \mathrm{m}$$ from the plate. What is the electric potential energy of the proton relative to the plate?

Accepted Answer

$$U = 2.4 	imes 10$$^{-17}$$\ \mathrm{J}$$

Question 2

If an electron is released in the same uniform electric field as above, at the same position, what direction will it move?

Accepted Answer

Upwards, away from the plate

Question 3

Which of the following statements is TRUE about the movement of a charged particle in an electric field?

Accepted Answer

A charged particle always moves toward lower potential energy

Question 4

Given the formula for electric potential energy in a uniform electric field, $$U = q|\vec{E}|y$$, what is the potential energy of an electron ($$q = -1.6 	imes 10$$^{-19}$$\ \mathrm{C}) $$located $$1.0\ \mathrm{m}$$ from a negatively charged plate in a field of $$150\ \mathrm{N/C}$$?

Accepted Answer

$$U = -2.4 	imes 10$$^{-17}$$\ \mathrm{J}$$

Question 5

A proton is released from rest in a uniform electric field. As it moves, what happens to its electric potential energy and kinetic energy?

Accepted Answer

Electric potential energy decreases, kinetic energy increases

Question 6

If the electric field points downward and $$y is $$measured upward from the plate ($$y=0 at $$the plate), what is the sign of the electric potential energy for a positive charge located above the plate?

Accepted Answer

Positive

Question 7

Which of the following best describes the direction of the electric field created by a negatively charged plate?

Accepted Answer

Toward the plate

Question 8

A proton and an electron are both placed $$1.0\ \mathrm{m}$$ from a negatively charged plate in a uniform electric field of $$150\ \mathrm{N/C}. $$Which particle has the greater magnitude of electric potential energy?

Accepted Answer

Both have the same magnitude

Question 9

If a charged particle moves in the direction of the electric field, what happens to its electric potential energy?

Accepted Answer

It decreases

Question 10

Which of the following is analogous to the formula for electric potential energy $$U = q|\vec{E}|y in $$gravitational systems?

Accepted Answer

$$E_p = mgy$$

Question 11

A proton is released from rest in a uniform electric field pointing downward. What is the direction of its acceleration?

Accepted Answer

Downward

Question 12

An electron is released from rest in a uniform electric field pointing downward. What is the direction of its acceleration?

Accepted Answer

Upward

Question 13

If the electric field is doubled while keeping the charge and position constant, what happens to the electric potential energy of the particle?

Accepted Answer

It is doubled

Question 14

Which of the following is NOT a correct statement about electric potential energy?

Accepted Answer

It is always positive

Question 15

A proton is released from rest in a uniform electric field and moves toward a negatively charged plate. What happens to its speed as it approaches the plate?

Accepted Answer

It increases

Question 16

If $$y=0 is $$chosen at the plate, what is the electric potential energy of a charge located at the plate?

Accepted Answer

It is zero

Question 17

Which of the following best explains why a particle in an electric field moves toward lower potential energy?

Accepted Answer

Because the field does work on the particle, converting potential energy to kinetic energy

Question 18

If a proton is released from rest and moves $$1.0\ \mathrm{m} in a $$uniform electric field of $$150\ \mathrm{N/C}$$, what is the change in its electric potential energy?

Accepted Answer

$$\Delta U = 2.4 	imes 10$$^{-17}$$\ \mathrm{J}$$

Question 19

If the electric field points downward and a positive charge is placed above the plate, what is the direction of the force on the charge?

Accepted Answer

Downward

week 8

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