Question

How many electrons are needed to form a charge of –2.00 nC? (b) How many electrons must be removed from a neutral object to leave a net charge of 0.500 µC?

a) (3.125 X 10¹3) electrons; (b) (3.125 X 10¹2) electrons
b) (1.25 X 10¹3) electrons; (b) (1.25 X 10¹2) electrons
c) (6.25 X 10¹3) electrons; (b) (6.25 X 10¹2) electrons
d) (2.5 X 10¹3) electrons; (b) (2.5 X 10¹2) electrons

Answer 1

To form a charge of -2.00 nC, 1.25×10^13 electrons are needed. To leave a net charge of 0.500 μC on an object, 3.125×10^12 electrons must be removed. Hence, the correct answer is option B.

Step-by-step explanation:

To determine how many electrons are needed to form a charge of -2.00 nC, we use the fact that the charge of one electron is approximately -1.60×10-19 coulombs (C). Therefore, the number of electrons needed can be calculated by dividing the total charge by the charge of one electron:

(a) Number of electrons = Total charge / Charge per electron = -2.00×10-9 C / -1.60×10-19 C/e- = 1.25×1010 electrons

Similarly, to find how many electrons must be removed to leave a net charge of 0.500 μC, we divide 0.500×10-6 C by the charge per electron:

(b) Number of electrons = 0.500×10-6 C / 1.60×10-19 C/e- = 3.125×1012 electrons

The correct answer to the student's question is (a) 1.25×1013 electrons are needed to form a charge of -2.00 nC, and (b) 3.125×1012 electrons must be removed from a neutral object to leave a net charge of 0.500 μC. Therefore, option B is correct.