Question 1

Which of the following best describes the principle demonstrated by Coulomb’s torsion balance experiment as shown in the image?

Accepted Answer

It measures the electrostatic force between charged objects, confirming that the force varies inversely with the square of the distance between them.

Question 2

Given two point charges, $$q_1$$ and $$q_2$$, separated by a distance $$r$$, which equation correctly gives the magnitude of the electrostatic force between them?

Accepted Answer

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

Question 3

In the scenario where a plastic sphere with charge $$q_1 = -10$$\ \mathrm{nC}$$ is held 1.0 cm above a glass bead with charge q_2$ = +10\ \mathrm{nC}$$ and mass $$15\ \mathrm{mg}$$, what is the direction of the electrostatic force on the glass bead?

Accepted Answer

Upward, toward the plastic sphere

Question 4

If the electrostatic force $$F_{1\ on\ 2}$$ between the plastic sphere and the glass bead is $$9.0 	imes 10$$^{-3}$$\ \mathrm{N}$$ and the weight of the bead is $$1.5 	imes 10$$^{-4}$$\ \mathrm{N}$$, what will happen to the bead?

Accepted Answer

The bead will leap upward toward the plastic sphere.

Question 5

Which of the following statements about the superposition principle is correct?

Accepted Answer

The net force on a charge is the vector sum of the forces exerted by each individual charge.

Question 6

A dipole consists of charges $$+q$$ and $$-q$$ separated by a distance $$d. If $$placed near a large negative charge, what is the net force on the dipole?

Accepted Answer

To the left

Question 7

Which of the following best describes the concept of an electric field?

Accepted Answer

A region where a charged particle experiences a force due to another charge.

Question 8

If the distance between two point charges is doubled, how does the magnitude of the electrostatic force between them change?

Accepted Answer

It becomes one-fourth as large.

Question 9

Which of the following is a correct expression for the weight $$w of an $$object with mass $$m$$ near the Earth's surface?

Accepted Answer

$$w = m g$$

Question 10

A charged particle is placed in a uniform electric field. Which of the following statements is true about its motion?

Accepted Answer

It will accelerate in the direction of the electric field if the charge is positive.

Question 11

Which of the following is NOT a property of Coulomb’s Law?

Accepted Answer

The force is independent of the sign of the charges.

Question 12

If three point charges are arranged in a triangle, how do you determine the net force on one of the charges?

Accepted Answer

By taking the vector sum of the forces from the other two charges.

Question 13

Which of the following best describes polarization in the context of electric charge?

Accepted Answer

The separation of positive and negative charges within an object.

Question 14

A glass rod is rubbed with silk, and the rod becomes positively charged. What happens to the silk?

Accepted Answer

It becomes negatively charged.

Question 15

Which of the following is the correct SI unit for electric charge?

Accepted Answer

Coulomb (C)

Question 16

If a charged object is brought near a neutral conductor and the conductor is then grounded, what is the result?

Accepted Answer

The conductor acquires a charge opposite to that of the nearby object.

Week 1 Lec. 2

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