An Fe3+ ion is located 400 nm (400 x 10-9 m, about 4000 atomic diameters) from a
ID: 1573569 • Letter: A
Question
An Fe3+ ion is located 400 nm (400 x 10-9 m, about 4000 atomic diameters) from a Cl- ion, as shown in the figure below (ions not shown to scale). 400 nm × Cl- Fe3. (a) Determine the magnitude and direction of the electric field E4 at location A, r = 101 nm to the left of the Cl-ion. magnitude direction N/C ..Select (b) Determine the magnitude and direction of the electric field Es at location B, magnitude direction Select. 101 nm to the right of the Cl-ion. N/C (c) If an electron is placed at location A, what are the magnitude and direction of the force on the electron? magnitude direction Select.Explanation / Answer
let q1 = 3*e = 3*1.6*10^-19 = 4.8*10^-19 C
q2 = -e = -1.6*10^-19 C
a) at point A,
Enet = |E1| + |E2|
= k*q1/r1^2 + k*q2/r2^2
= 9*10^9*4.8*10^-19/(299*10^-9)^2 + 9*10^9*1.6*10^-19/(101*10^-9)^2
= 1.89*10^5 N/c
direction : towards +x axis
b) at point B,
Enet = |E1| - |E2|
= k*q1/r1^2 + k*q2/r2^2
= 9*10^9*4.8*10^-19/(501*10^-9)^2 - 9*10^9*1.6*10^-19/(101*10^-9)^2
= 1.24*10^5 N/c
direction : towards -x axis
c) F = q*Enet
= 1.6*10^-19*1.89*10^5
= 3.02*10^-14 N
direction : towards -x axis