Question 1

Which of the following statements about electric charge is INCORRECT?

Accepted Answer

There is no difference between charge and current.

Question 2

A glass rod is rubbed with silk, and then brought near small pieces of paper. The rod attracts the paper because:

Accepted Answer

The rod becomes positively charged and induces a charge separation in the paper.

Question 3

Which of the following best describes the difference between conductors and insulators?

Accepted Answer

Conductors allow free movement of electrons, while insulators do not.

Question 4

Two identical conducting spheres, one with charge $$+Q$$ and the other uncharged, are brought into contact and then separated. What is the final charge on each sphere?

Accepted Answer

$$+\frac{Q}{2}$$

Question 5

A negatively charged rod is brought near (but does not touch) a neutral metal sphere, and the sphere is then grounded on the side opposite the rod. After removing the ground and the rod, what is the net charge on the sphere?

Accepted Answer

Positive

Question 6

Which of the following is the correct mathematical expression for Coulomb’s Law for the magnitude of the force between two point charges $$q_1$$ and $$q_2$$ separated by a distance $$r$$?

Accepted Answer

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

Question 7

Three pithballs are suspended from threads. Pithballs 1 and 2 repel each other, and pithballs 2 and 3 repel each other. What can you conclude?

Accepted Answer

All three carry charges of the same sign.

Question 8

A negatively charged object A attracts object B. Which state(s) are possible for object B?

Accepted Answer

B is positively charged or neutral.

Question 9

Which of the following is NOT a property of conductors in electrostatic equilibrium?

Accepted Answer

The electric field just outside the conductor is parallel to the surface.

Question 10

A hydrogen atom consists of a proton and an electron separated by $$5.3 	imes 10$$^{-11}$$ m. Calculate the ratio of the magnitude of the electric force to the gravitational force between them. (Given: k_e = 8.99$$ 	imes $$10^9 Nm$^2/C$^2$$, $$e = 1.6 	imes 10$$^{-19}$$ C, G = 6.67$$ 	imes $$10^{-11} Nm$^2/kg$^2$$, $$m_p = 1.67 	imes 10$$^{-27}$$ kg, m_e = 9.11$$ 	imes $$10^{-31} kg)$$

Accepted Answer

$$\approx 10$$^{39}$$

Question 11

Which of the following best describes the direction of the electric field produced by a positive point charge?

Accepted Answer

Radially outward from the charge.

Question 12

The electric field at a point is defined as:

Accepted Answer

$$\vec{E} = \frac{\vec{F}}{q_0$}$$

Question 13

Which of the following is a correct statement about electric field lines?

Accepted Answer

Electric field lines never intersect.

Question 14

A parallel-plate capacitor consists of two large plates with equal and opposite charges. According to Gauss’s Law, what is the electric field between the plates (neglecting edge effects)?

Accepted Answer

$$E = \frac{\sigma}{\$$varepsilon_0$$}$$

Question 15

A uniformly charged spherical shell exerts what electric field at a point inside the shell?

Accepted Answer

Zero

Question 16

Which of the following is the correct expression for the electric flux $$\Phi_E$$ through a surface area $$A in a $$uniform electric field $$E at an $$angle $$	heta to $$the normal?

Accepted Answer

$$\Phi_E = EA \cos 	heta$$

Question 17

According to Gauss’s Law, the net electric flux through any closed surface is:

Accepted Answer

$$\frac{Q_{	ext{enclosed}}}{\$$varepsilon_0$$}$$

Question 18

A charged cylindrical shell of radius $$r$$ and length $$\ell is $$placed in a uniform electric field $$E$$ parallel to its axis. What is the net electric flux through the surface of the cylinder?

Accepted Answer

Zero

Question 19

Which of the following is a consequence of the superposition principle for electric fields?

Accepted Answer

The net electric field is the vector sum of the fields produced by each charge.

PHYS 102: Introductory Physics II – Study Notes on Electric Charge, Force, and Field

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