Chapter 14 Electrostatics Date: ______________

Section A: Multiple Choice Questions

1 Amy uses a piece of silk to rub a comb. The comb then becomes positively charged. This net

positive charge accumulates because the comb

A. gains electrons. B. gains protons.

C. loses electrons. D. loses protons.

2 The diagram shows the electric field lines between two electrical charges P and Q. Which of the

following statements about the charges on P and Q is correct?

A. P is positive and Q is negative.

B. P is negative and Q is positive.

C. P and Q are both positive.

D. The electric field lines only show the intensity of

the electric field but not the charges.

3 John draws the following diagrams to illustrate the electric field between two charged objects. Which

of them is incorrect?

A.

B.

C.

D.

4 Which of the following should not be done during lightning?

(1) Stay in a building with a lightning conductor installed on the roof.

(2) Stand near a window with a metal frame.

(3) Crouch down in an open field.

A. (1) only B. (2) only

C. (1) and (2) only D. (2) and (3) only

5 A metallic object is given a net positive charge by induction. What is the change in the mass of the

object?

A. Increases B. Decreases

C. Remains unchanged D. It cannot be determined.

6 A child rubs a rubber ruler and then puts it near some tiny pieces of paper. The paper pieces are

then attracted to the ruler. Which of the following statements best explains the result?

A. Paper is naturally a negative material.

B. Rubber and paper always attract each other. C. The paper becomes charged by induction.

D. The paper acquires a net positive charge by induction.

(14)Electrostatics.doc

7 A teacher rubs a rubber rod with a fur during a class and finds out that the rod becomes negatively

charged. What has happened between the rod and the fur?

A. The protons in the rod are transferred to the fur.

B. The electrons in the rod are transferred to the fur.

C. The protons in the fur are transferred to the rod.

D. The electrons in the fur are transferred to the rod.

8 The diagram shows the electric field lines of a negative point charge. The strength of the electric

field is

A. the greatest at point P.

B. the greatest at point Q.

C. the greatest at point R.

D. the same at the three points.

9 Which of the following statements concerning lightning is / are correct?

(1) It is a result of charging.

(2) The charges at the bottom of the clouds and those induced on the top of the roofs of buildings

form a very strong electric field.

(3) Lightning causes the thunder we heard.

A. (1) only B. (1) and (2) only

C. (2) and (3) only D. (1), (2) and (3)

10 The diagram shows five charged metal spheres suspended by strings. The charge of each sphere is

+5 C, −2 C, +3 C, −4 C and +2 C as shown. If the five spheres simultaneously contact together, find

the net charge on them.

A. +16 C

B. +4 C

C. −4 C

D. −16 C

11 Two spheres P and Q are supported on two insulated stands and placed next to each other. Sphere

P has a charge of +10 C and sphere Q is neutral. Which of the following statements is correct?

A. P and Q together have a net charge of +5 C.

B. After some time, Q becomes negatively charged.

C. After some time, the charges on P are transferred to Q.

D. After some time, Q is still neutral.

12 A neutral object loses 3 electrons. What is the net charge of it?

A. −3 C B. +3 C

C. −4.8 × 10−19 C D. +4.8 × 10−19 C

(14)Electrostatics.doc

Section B: Questions

1 (a) Define a conductor and an insulator.

Ans:

(b) Name two examples for conductors and insulators respectively.

Ans:

2 There are two horizontal plates X and Y and a neutral conducting sphere S placed between

them as shown.

(a) Complete the circuit by drawing the symbol of a battery so that electrons can flow

from plate X through the battery to the plate Y.

(b) In the above diagram, indicate the charges on the plates and that induced on the

sphere.

(c) Explain briefly why the sphere falls towards plate Y. What will happen after S hits the

plate?

Ans:

(14)Electrostatics.doc

3 The diagram shows two metal plates. One of them is positively charged while another is

negatively charged.

(a) Draw the electric field lines to represent the electric field between the plates.

(b) If a test charge is placed between the plates, where will the test charge be

experienced the strongest force? Explain briefly with the help of the electric field lines

you drawn in (a).

Ans:

End

(14)Electrostatics.doc