Physics Review Question

Unit: Electricity & Magnetism
Year: 1988 Question#: 28
Question: An oil drop has a charge of -4.8 x 10-19 coulomb. How many excess electrons does the oil drop have?

(1 ) 1.6 x 10-19
(2 ) 2.0
(3 ) 3.0
(4 ) 6.3 x 1018

What is this question really asking?




Explanation by: Yui H.

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Answer 1
1.6 x 10-19

incorrect

This answer is incorrect because in order to get the number of excess electrons, the charge of an substance is divided by the one elementary charge of the electron(constant). When -4.8 x 10-19 is divided by 1.6 x 10-19 (constant) the answer is 3.0 Answer #1 is number of one elementary charge of the electron. return to top























Answer 2
2.0

incorrect

This answer is incorrect because in order to get the number of excess electrons, the charge of an substance is divided by the one elementary charge of the electron(constant). When -4.8 x 10-19 is divided by 1.6 x 10-19 (constant) the answer is 3.0 It does not equal 2.0 return to top



























Answer 3
3.0

correct

This answer is correct because in order to get the number of excess electrons, the charge of an substance is divided by the one elementary charge of the electron(constant). When -4.8 x 10-19 is divided by 1.6 x 10-19 (constant) the answer is 3.0 return to top


























Answer 4
6.3 times 1018

incorrect

This answer is incorrect because in order to get the number of excess electrons, the charge of an substance is divided by the one elementary charge of the electron(constant). When -4.8 x 10-19 is divided by 1.6 x 10-19 (constant) the answer is 3.0 Answer #4 represents one coulomb (constant). return to top


























What's this question really asking?

How many excess electrons does the oil drop have? Also this question is testing your ability to use the reference table. return to top

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