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inner radius 20 cm and A particle with a charge of -60.0 nc is placed at the cen

ID: 1532317 • Letter: I

Question

inner radius 20 cm and A particle with a charge of -60.0 nc is placed at the center of a nonconducting spherical shell of outer radius 21.0 cm. The spherical shell carries charge with a uniform density of -1.99 Ho/m3. A proton moves in a circular orbit just outside the spherical shell. Calculate the speed of the proton. 5.9 10 5 Your response is within 10% of the correct value. This may be due to roundoff error, or you could have a mistake in your calculation. Carry out a intermediate results to at least four-digit accuracy to minimize roundoff error. m/s Need Help? Read It

Explanation / Answer


(A)
given q = -60 nC , ri = 20.0 cm , ro = 21.0 cm

Field at E1 = q/4*pi*Eo*ro^2

= (60*10^-9)*9*10^9/(0.21)^2

= 12244.89 N/C

Field due to shell is found by intgration ri to ro

E2 = (4/3)*pi*P*(ro^3-ri^3)/4*pi*Eo*ro^2

= (9*10^9)*(4/3*pi*1.99*10^-6)*(0.21^3-0.20^3)/0.21^2

= 2145.16 N/C

total field E = E1 + E2

= 14390.05 N/C

Force on proton = q*E

= 1.6*10^-19*14390.05

= 2.302*10^-15 N

m*v^2/ro = 2.302*10^-15

v = squrt( 2.302*10^-15*0.21)/1.672*10^-27

= 5.37*10^5 m/s

(B)

1. r<a,from Gauss law

the charge enclosed in the loop is the linear charge density

integration (E*ds) = q/E0

E*(2*pi*r*L) = (4*pi)*(lembda*L)/4*pi*E0

E*(2*pi*r*L) = (4*pi*k)*(lembda*L)

E = (2*pi*k)/r

2. a<r<b, the volume of the charge from the cylindrical shell that would be enclosed by the gassian surface is

v = pi*r^2*L -pi*a^2*L

= pi*L(r^2-a^2)

From the Gauss's law

E*(2*pi*r*L) = (4*pi*k)*[(lembda*L)+p*pi*L(r^2-a^2)]

E = 2k*[lembda + p*pi*(r^2-a^2)]/r

3. r>b, the same procedure as above

v = pi*b^2*L -pi*a^2*L

= pi*L(b^2-a^2)

E*(2*pi*r*L) = (4*pi*k)*[(lembda*L)+p*pi*L(b^2-a^2)]

E = 2k*[lembda + p*pi*(b^2-a^2)]/r