A nonconducting sphere 1.0 m in diameter with its center on the x axis at x = 4
ID: 2009535 • Letter: A
Question
A nonconducting sphere 1.0 m in diameter with its center on the x axis at x = 4 m carries a uniform volume charge of density = 3.3 µC/m3. Surrounding the sphere is a spherical shell with a diameter of 2.0 m and a uniform surface charge density = -1 µC/m2. Calculate the magnitude and direction of the electric field at the following locations.
(a) x = 4.4 m, y = 0
_____I N/C ______J N/C
(b) x = 4 m, y = 0.9 m
______ I N/C _______ J N/C
(c) x = 2.0 m, y = 2.0 m
_______ I N/C _______ J N/C
I really don't know where to begin this problem, if you can please help me get started, i would highly appreciate it. Thanks.
Explanation / Answer
diameter of nonconducting sphere d1 = 1 m radius of the sphere R1 = 0.5 m diameter of the spherical shell d2 = 2 m radius of the spherical shell R2 = 1 m volume charge density = 3.3 µC/m3 surface charge density = -1 µC/m2 electric field due to nonconducting shere and spherical shell is E = E1 + E2 .................. (1) where , E1 = electric field due to nonconducting shere E2 = electric field due to spherical shell a) at x = 4.4 m and y = 0 m (inside the spherical shell) : the electric field, inside the spherical shell is zero. so , at this point E2 = 0 the electric field E1 = (4/3)(kd) i^ where , d = 4.4 m - 4 m = 0.4 m the electric field E1 = (4/3)(3.14*9*109*3.3*10-6)(0.4) i^ = (49.73*103 N/C) i^ substitute these values in eq (1) , we get E = (49.73*103 N/C) i^ + 0 = (49.73*103 N/C) i^ + 0 j^direction : = tan-1 (0/49.73*103) = 00 ...................................................................... b) ...................................................................... at x = 4 m and y = 0.9 m (inside the spherical shell) : the electric field, inside the spherical shell is zero. so , at this point E2 = 0 for x = 4 m : the electric field E1 = (4/3)(kd') i^ where , d' = 4 m - 4 m = 0 m the electric field E1 = (4/3)(3.14*9*109*3.3*10-6)(0) i^ = 0 for y = 0.9 m : electric field E2 = (4/3y2)[k(R1)3] j^ = (4*3.14/3(0.9)2)[9*109*3.3*10-6*(0.5)3] j^ = (57.567*103 N/C) j^ substitute these values in eq (1) , we get electric field E = 0 i^ + (57.567*103 N/C) j^ direction : = tan-1 (57.567*103 /0) = 900
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........................................................................... at x =2 m and y = 2 m , charge qshell = Ashell = [4R22] = (-1*10-6)(4)(3.14)(1)2 = -12.56*10-6 C charge of the sphere is qsphere = Vsphere = [(4/3)R13] = (3.3*10-6)(4/3)(3.14)(0.5)3 = 1.727*10-6 C if x = 2 and y = 2 , r = 22 + 22 = 8 = 2.828 m unit vector r^ = -2/2.828 i^ + 2.828/2 j^ = -0.7071 i^ + 0.7071 j^ .............................................................................. electric field E shell is E2 = E shell = [k(qshell)(r^)] / r2 = [9*109*(-12.56)*10-6*(-0.7071 i^ + 0.7071 j^)] / (2.828)2 = [9.99*103 i^ - 9.99*103 j^] N/C electric field Esphere is E1 = Esphere = [k(qsphere)(r^)] / r2 = [9*109*1.727*10-6*(-0.7071 i^ + 0.7071 j^)] / (2.828)2 = [-1.3742*103 i^ + 1.3742*103 j^] N/C substitute these values in eq (1) , we get E = 8.615*103 i^ - 8.615*103 j^
direction : = tan-1 (-8.615*103/8.615*103) = -450 ............................................................................... answers : a) E = (49.73*103 N/C) i^ + 0 j^ b) E = 0 i^ + (57.567*103 N/C) j^ c) E = 8.615*103 i^ - 8.615*103 j^ the electric field, inside the spherical shell is zero. so , at this point E2 = 0 for x = 4 m : the electric field E1 = (4/3)(kd') i^ where , d' = 4 m - 4 m = 0 m the electric field E1 = (4/3)(3.14*9*109*3.3*10-6)(0) i^ = 0 for y = 0.9 m : for y = 0.9 m : electric field E2 = (4/3y2)[k(R1)3] j^ = (4*3.14/3(0.9)2)[9*109*3.3*10-6*(0.5)3] j^ = (57.567*103 N/C) j^ substitute these values in eq (1) , we get electric field E = 0 i^ + (57.567*103 N/C) j^ direction : = tan-1 (57.567*103 /0) = 900
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........................................................................... at x =2 m and y = 2 m , charge qshell = Ashell = [4R22] = (-1*10-6)(4)(3.14)(1)2 = -12.56*10-6 C charge of the sphere is qsphere = Vsphere = [(4/3)R13] = (3.3*10-6)(4/3)(3.14)(0.5)3 = 1.727*10-6 C if x = 2 and y = 2 , r = 22 + 22 = 8 = 2.828 m unit vector r^ = -2/2.828 i^ + 2.828/2 j^ = -0.7071 i^ + 0.7071 j^ .............................................................................. = 1.727*10-6 C if x = 2 and y = 2 , r = 22 + 22 = 8 = 2.828 m unit vector r^ = -2/2.828 i^ + 2.828/2 j^ = -0.7071 i^ + 0.7071 j^ .............................................................................. electric field E shell is E2 = E shell = [k(qshell)(r^)] / r2 = [9*109*(-12.56)*10-6*(-0.7071 i^ + 0.7071 j^)] / (2.828)2 = [9*109*(-12.56)*10-6*(-0.7071 i^ + 0.7071 j^)] / (2.828)2 = [9.99*103 i^ - 9.99*103 j^] N/C electric field Esphere is E1 = Esphere = [k(qsphere)(r^)] / r2 = [9*109*1.727*10-6*(-0.7071 i^ + 0.7071 j^)] / (2.828)2 = [-1.3742*103 i^ + 1.3742*103 j^] N/C substitute these values in eq (1) , we get E = 8.615*103 i^ - 8.615*103 j^
direction : = tan-1 (-8.615*103/8.615*103) = -450 ............................................................................... answers : a) E = (49.73*103 N/C) i^ + 0 j^ b) E = 0 i^ + (57.567*103 N/C) j^ c) E = 8.615*103 i^ - 8.615*103 j^ = [9*109*1.727*10-6*(-0.7071 i^ + 0.7071 j^)] / (2.828)2 = [-1.3742*103 i^ + 1.3742*103 j^] N/C substitute these values in eq (1) , we get E = 8.615*103 i^ - 8.615*103 j^
direction : = tan-1 (-8.615*103/8.615*103) = -450 ............................................................................... answers : a) E = (49.73*103 N/C) i^ + 0 j^ b) E = 0 i^ + (57.567*103 N/C) j^ c) E = 8.615*103 i^ - 8.615*103 j^ ............................................................................... answers : a) E = (49.73*103 N/C) i^ + 0 j^ b) E = 0 i^ + (57.567*103 N/C) j^ c) E = 8.615*103 i^ - 8.615*103 j^ b) E = 0 i^ + (57.567*103 N/C) j^ c) E = 8.615*103 i^ - 8.615*103 j^
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