o 2/14/2018 1159 PM725/1002/14/201803:07 AM Pnnt Calaliilor bal Periodic Table Q
ID: 1872273 • Letter: O
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o 2/14/2018 1159 PM725/1002/14/201803:07 AM Pnnt Calaliilor bal Periodic Table Question 32 of 34 Map deb University Physícs presented by Bapling Leaming A red blood cell typically carries an excess charge of about-2.5 x10- disributed uniformly over its surface. The red blood cells can be modeled as spheres approximately 6.6 in diameter and a mass of 9.0x10 *kg. How many excess electrons does a typical red blood cell have? Number electrons Does the mass of the extra electrons appreciably affect the mass of the cell? To find out, calculate the ratio of the mass of the extra electrons to the mass of the cell without the excess charge. Number What is the surface charge density on the red blood cel? Express your answer in units of C/m2 and Number C/ m Number electrons / m O Previous Gwe Up & View Solut on O check Answer 0 Next Exit HintExplanation / Answer
Q = n e
(2.5 x 10^-12) = n (1.6 x 10^-19)
n = 1.56 x 10^7 electrons .....Ans
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m = (1.56 x 10^7) (9.109 x 10^-31)
= 1.423 x 10^-23 kg
ratio = (1.423 x10^-23) / (9 x 10^-14)
= 1.58 x 10^-10
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surface charge density = Q / (4 pi r^2)
= - 0.0183 C / m^2 ......Ans
Or (1.56 x 10^7 ) / (4 pi r^2)
= 1.14 x 10^17 electrons / m^2 ......Ans
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