Question

If a cat repeatedly rubs against your cotton slacks on a dry day, the charge transfer between the cat hair and the cotton can leave you with an excess charge of -4.90 μC. (a) How many electrons are transferred between you and the cat? You will gradually discharge via the floor, but if instead of waiting, you immediately reach toward a faucet, a painful spark can suddenly appear as your fingers near the faucet. (b) In that spark, do electrons flow from you to the faucet or vice versa ? (c) Just before the spark appears, do you induce positive or negative charge in the faucet? (d) If, instead, the cat reaches a paw toward the faucet, which way do electrons flow in the resulting spark, from faucet to the cat or vice versa?

Answer 1

About 3.06 x 10^13 electrons are transferred between the cat and a person, causing them to gain a negative charge. Electrons flow from the negatively charged person to the faucet, inducing a positive charge in the faucet before the spark. If the cat with a positive charge reaches out, electrons flow from the faucet to the cat.

Step-by-step explanation:

If a cat repeatedly rubs against your cotton slacks on a dry day, and this results in an excess charge of -4.90 µC (microcoulombs) on you, we need to calculate how many electrons are transferred. The charge of one electron is approximately -1.6 x 10-19 coulombs. Therefore, the number of electrons transferred can be found by dividing the total charge by the charge of one electron:

-4.90 µC / (-1.6 x 10-19 C/electron) = 3.06 x 1013 electrons.

Answer to Part (a)

Approximately 3.06 x 1013 electrons are transferred between the cat and you.

Answer to Part (b)

Since you gain a negative charge, the electrons flow from you to the faucet when you reach toward it and experience the spark.

Answer to Part (c)

Before the spark, you would induce a positive charge in the faucet due to the repulsion of like charges (negativecharges in you repel the electrons in the faucet, leaving the near side more positively charged).

Answer to Part (d)

If the cat, with its excess positive charge, reached a paw toward the faucet, electrons would flow from the faucet to the cat in the resulting spark.

Answer 2

• The number of electrons transferred is
  `3.0625 \ 10^(13)`
• The electrons flow from you to the faucet.
• You induce a positive charge in the faucet.
• The electrons flow from the faucet to the cat.

Step-by-step explanation:

a)

The number of electrons will be given by

`number \ of \ electrons = (charge \ transferred)/(charge \ of \ the \ electron)`

so, we have:

`number \ of \ electrons = ( - 4.90 \mu C)/(- 1.602 \ 10^(-19) \ C)`

`number \ of \ electrons = 3.0625 \ 10^(13)`

b)

The electrons flow from you, that are charged with electrons, to the faucet, that is discharged.

c)

As you approach the faucet, the electrons in your body will repel the electrons in the faucet, inducing a positive charge in it.

d)

The cat is charged with a positive charge, as many electron originally from him were transferred to your body, when the cat touch the faucet, the electrons will flow to the cat.