If a cat repeatedly rubs against your cotton slacks on a dry day, the charge tra

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 -5.10 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 (type 1) or vice versa (type 0)? (c) Just before the spark appears, do you induce positive (type 1) or negative (type 0) 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 - type 1, or vice versa - type 0)?

Explanation / Answer

(a)

1 electron = 1.602 x10-19 C

-5.10 x 10-6 C (1 electron / 1.602 x10-19 C) = 3.18 x 1013 electrons   

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(b) type 1 (you to faucet)

you have EXCESS electrons compaire to the earth,

when you touch the faucet, the electrons will distribute themselves so that you and the earth will have the same charge

thus SOME or ALL of the excess electrons will flow TO the faucet

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(c)type 1 (positive)

you are negatively charged, so as you go near the faucet, YOU REPEL the electrons in the faucet

the faucet electrons MOVE AWAY from you, leaving a POSITIVE INDUCED charge on the part of the faucet near you

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(d) type 1(faucet to cat)

the cat has transgferred 3.18 x 1013 electrons to you

that means the cat lacks these electrons and is positively charged (+5.10 microC) compared to its surroundings

when it touches the faucet, the some electrons in the faucet will distribute themselves TO THE CAT'S BODY until the faucet and the cat has the same zero charge (portons in the cat = electrons in the cat)

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