You observe that a negatively charged plastic pen repels a charged piece of invisible tape. You then observe that the same piece of tape is repelled when brought near a metal sphere. You are wearing rubber-soled shoes, and you touch the metal sphere with your hand. After you touch the metal sphere, you observe that the tape is attracted to the metal sphere. Which of the following statements could be true? Check all that apply. (1) Electrons from the sphere traveled through your body into the Earth. (2) Electrons from the sphere moved into the salt water on your skin, where they reacted with sodium ions. (3) After you touched it, the metal sphere was very nearly neutral. (4) Chloride ions from the salt water on your hand moved onto the sphere. (5) The excess negative charge from the sphere spread out all over your body. (6) Electrons from your hand moved onto the sphere. (7) Sodium ions from the salt water on your hand moved onto the sphere.

Short Answer

Expert verified

Statement (2) is correct; Electronsfrom the sphere moved into the saltwater on your skin, where they reacted with sodium ions.

Statement (3) is correct,After you touched it, the metal sphere was very nearly neutral.

Statement (5) is correct,The excess negative charge from the sphere spread out all over your body

Statement (7) is correct, Sodium ions from the saltwater on your hand moved onto the sphere.

Step by step solution

01

Significance of the law of attraction

The law of attraction states that the unlike charges attract each other, and the like charges repel each other.

The concept of the law of attraction gives the correct statement

02

Determination of the correct statement

Statement (1) is incorrect as the “insulating shoe of rubber” mainly prevents the excess charges from discharging through Earth.

Statement (4) is incorrect as the sphere afterward attracts an object that carries a negative charge that indicates that the sphere is positively charged. Hence, the charge does not get transferred to the sphere.

Statement (6) is incorrect as the human body is an insulator, and hence no excess electrons move to the human body.

Statement (2) is correct as the negatively charged electrons mainly attract the sodium ions, which are positively charged. Hence, the charged sphere gets neutralized and forms sodium ions.

Statement (3) is correct because the sodium ions attract the electrons that neutralize the charged sphere, but the negative object attracts the charged sphere. Hence, a small portion of the sodium ion mainly gets transferred to the sphere.

Statement (5) is correct because the charged particle mainly works as a conductor with excess charges on the surface that eventually get equally redistributed to the human body and the sphere itself.

Statement (7) is correct as the sodium ions are positively charged, and as the sphere got attracted to the object which contained a negative charge, then the sphere has some amount of positive charge. The sodium ions also must get transferred to the sphere.

Thus, the statement (2), (3), (5), and (7) are correct.

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Most popular questions from this chapter

A very thin spherical plastic shell of radius15 cm carries a uniformly distributed negative charge of 8 nC(8×109 C)on its outer surface (so it makes an electric field as though all the charge were concentrated at the center of the sphere). An uncharged solid metal block is placed nearby. The block is10cm thick, and it is10cm away from the surface of the sphere. See Figure 14.97. (a) Sketch the approximate charge distribution of the neutral solid metal block.

(b) Draw the electric field vector at the center of the metal block that is due solely to the charge distribution you sketched (that is, excluding the contributions of the sphere).

(c) Calculate the magnitude of the electric field vector you drew. Explain briefly. If you must make any approximations, state what they are.

You rub a clear plastic pen with wool, and observe that a strip of invisible tape is attracted to the pen. Assuming that the pen has a net negative charge, which of the following could be true? Select all that apply. (1) The tape might be negatively charged. (2) The tape might be positively charged. (3) The tape might be uncharged. (4) There is not enough information to conclude anything.

You place a neutral block of nickel near a small glass sphere that has a charge of 2×10-8Cuniformly distributed over its surface, as shown in Figure 14.92.


(a) About how long do you have to wait to make sure that the mobile electron sea inside the nickel block has reached equilibrium? (1) Less than a nanosecond (1×10-9s), (2) Several hours, (3) About 1s, (4) About 10min(b) In equilibrium, what is the average drift speed of the mobile electrons inside the nickel block? (1) About 1×105m/s, (2) About 1×10-5m/s, (3) 0m/s(c) In the equation v¯=uE, what is the meaning of the symbol u? (1) The density of mobile electrons inside the metal, in localid="1657175774793" electrons/m3, (2) The mobility of an electron inside the metal, in m/s/N/C, (3) The time it takes a block of metal to reach equilibrium, in seconds

You run your finger along the slick side of a positively charged tape, and then observe that the tape is no longer attracted to your hand. Which of the following are not plausible explanations for this observation? Check all that apply. (1) Sodium ions (Na+) from the salt water on your skin move onto the tape, leaving the tape with a zero (or very small) net charge. (2) Electrons from the mobile electron sea in your hand move onto the tape, leaving the tape with a zero (or very small) net charge. (3) Chloride ions (CI-) from the salt water on your skin move onto the tape, leaving the tape with a zero (or very small) net charge. (4) Protons are pulled out of the nuclei of atoms in the tape and move onto your finger.

Atom Ais easier to polarize than atom B. Which atom, Aor B, would experience a greater attraction to a point charge a distance raway? Explain your reasoning.

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