Question 1

Which of the following statements about triboelectric charging is NOT true based on the provided triboelectric series?

Accepted Answer

If human hair is rubbed with silk, it becomes negatively charged.

Question 2

A +1 C probe charge is placed at the origin, equidistant from two +2 C charges on the y-axis and two -3 C charges on the z-axis. In which direction does the probe charge experience a net force?

Accepted Answer

No net force

Question 3

If a cone-shaped iron weight is charged with +Q, which of the following statements is NOT true?

Accepted Answer

The electric field line densities across the surface of the iron weight are uniform (i.e., constant).

Question 4

A proton and an electron are released from rest at positions where the electric potential is 0 V. The proton moves to the left, while the electron moves to the right. Why does this occur?

Accepted Answer

Positive charges move toward lower potential, negative charges move toward higher potential.

Question 5

Which material in the triboelectric series is most likely to become positively charged when rubbed with Teflon?

Accepted Answer

Rabbit fur

Question 6

What is the primary reason a negative probe charge placed inside a conductor experiences no electric force?

Accepted Answer

The electric field inside a conductor is zero.

Question 7

Given the electric field lines between a positive and negative charge, as shown in the diagram, what is the direction of the electric field at a point midway between the two charges?

Accepted Answer

From the positive charge to the negative charge

Question 8

If a parallel-plate capacitor contains a dielectric material with dielectric constant $$k=2$$, how does its stored energy compare to an identical capacitor without a dielectric, assuming the same electric field strength?

Accepted Answer

The stored energy is doubled.

Question 9

Which equation correctly describes the energy stored in a parallel-plate capacitor with plate area $$A$$, separation $$d$$, and dielectric constant $$k$$?

Accepted Answer

$$U = \frac{1}{2} k \$$varepsilon_0$$ \frac{A}{d} V^2$

Question 10

If human hair is rubbed with silk, which material will become positively charged according to the triboelectric series?

Accepted Answer

Human hair

Question 11

A charged iron cone has a higher charge density at its vertex than at its base. What is the physical reason for this?

Accepted Answer

The electric field is stronger at regions of higher curvature.

Question 12

Which of the following statements about equipotential lines is correct?

Accepted Answer

The electric field is always perpendicular to equipotential lines.

Question 13

A parallel-plate capacitor with area $$A$$ and separation $$d is $$filled with a dielectric of constant $$k. If $$the voltage across the plates is $$V$$, what is the capacitance?

Accepted Answer

$$C = k \$$varepsilon_0$$ \frac{A}{d}$$

Question 14

If a positive charge is placed near a negative charge, what is the direction of the force experienced by the positive charge?

Accepted Answer

Toward the negative charge

Question 15

Which of the following best describes the distribution of charge on a conductor?

Accepted Answer

Charge resides only on the surface.

Question 16

If a capacitor is charged and then disconnected from the battery, what happens to the stored energy if a dielectric is inserted?

Accepted Answer

The stored energy decreases.

Question 17

Which equation describes the force between two point charges $$q_1$$ and $$q_2$$ separated by distance $$r$$?

Accepted Answer

$$F = \frac{1}{4\pi\$$varepsilon_0$$} \frac{q_1$ q_2$}{r^2$}$$

Question 18

Which material in the triboelectric series is most likely to become negatively charged when rubbed with glass?

Accepted Answer

Teflon

Question 19

If a positive charge moves from a region of 0 V to 500 V, what happens to its electric potential energy?

Accepted Answer

It increases.

Question 20

Which of the following is a correct statement about the electric field inside a charged conductor?

Accepted Answer

The electric field inside a conductor is zero.

Physics Study Guide: Electrostatics, Electric Fields, and Capacitors

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