Question 1

Which of the following statements about the conservation of electric charge is correct?

Accepted Answer

Electric charge is always conserved in an isolated system.

Question 2

A negatively charged ebonite rod is brought near a neutral metal sphere and touches it. After separation, what is the interaction between the rod and the sphere?

Accepted Answer

The rod is repelled by the sphere.

Question 3

Which device was invented in 1745 to store large amounts of electric charge and was crucial for early electrical experiments?

Accepted Answer

Leyden jar

Question 4

What is the SI unit of electric charge?

Accepted Answer

Coulomb

Question 5

How many electrons are there in one coulomb of negative charge? Use $$e = 1.60 	imes 10$$^{-19}$$ C.

Accepted Answer

$$6.25 	imes 10$$^{18}$$

Question 6

Which of the following materials is an electrical conductor?

Accepted Answer

Copper

Question 7

What is the main difference between the Bohr model and the Rutherford model of the atom?

Accepted Answer

Bohr model restricts electrons to definite shells, while Rutherford model allows any orbit.

Question 8

Which equation correctly expresses the relationship between charge, number of electrons, and elementary charge?

Accepted Answer

$$q = Ne$$

Question 9

A charged particle with charge $$q$$ and mass $$m is $$placed in a uniform electric field $$E. $$What is its acceleration?

Accepted Answer

$$a = \frac{qE}{m}$$

Question 10

Which historical experiment demonstrated that electricity could be generated by rotating a ball of sulfur against another object?

Accepted Answer

Otto von Guericke's sulfur ball experiment

Question 11

What is the force between two point charges $$q_1$$ and $$q_2$$ separated by a distance $$r in $$vacuum?

Accepted Answer

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

Question 12

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

Accepted Answer

It becomes one-fourth as strong.

Question 13

Which statement about electric field lines is FALSE?

Accepted Answer

Electric field lines can cross each other.

Question 14

A dipole consists of charges $$+q$$ and $$-q$$ separated by distance $$d. $$What is the magnitude of its dipole moment?

Accepted Answer

$$p = qd$$

Question 15

Which of the following is a real-world application of electric fields in biology?

Accepted Answer

DNA fingerprinting using electrophoresis

Question 16

What happens to the electric field strength if you double your distance from a dipole?

Accepted Answer

It becomes one-eighth as strong.

Question 17

Which process describes charging an object without direct contact?

Accepted Answer

Charging by induction

Question 18

Which scientist is credited with discovering the electron and measuring its charge-to-mass ratio?

Accepted Answer

J.J. Thomson

Question 19

What is the potential energy $$U of an $$electric dipole with moment $$\vec{p} in a $$uniform electric field $$\vec{E}$$?

Accepted Answer

$$U = -\vec{p} \cdot \vec{E}$$

Electric Forces and Electric Fields: Foundations and Historical Development

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