A metal sphere with radius r a = 1.30 cm is supported on an insulating stand at
ID: 1330107 • Letter: A
Question
A metal sphere with radius ra = 1.30 cm is supported on an insulating stand at the center of a hollow, metal, spherical shell with radius rb = 9.90 cm . Charge +q is put on the inner sphere and charge q on the outer spherical shell. The magnitude of q is chosen to make the potential difference between the spheres 420 V , with the inner sphere at higher potential.
Part A
Calculate q.
Part B
Are the electric field lines and equipotential surfaces mutually perpendicular?
Are the electric field lines and equipotential surfaces mutually perpendicular?
No
Part C
Are the equipotential surfaces closer together when the magnitude of E is largest?
YesNo
Part C
Are the equipotential surfaces closer together when the magnitude of E is largest?
Equipotential surfaces closer together when the magnitude of E is largest. Equipotential surfaces closer together when the magnitude of E is smallest.Explanation / Answer
A)
Capacitance of spherical capaciotr, C = 4*pi*epsilon/(1/a - 1/b)
= 4*pi*8.854*10^-12/(1/0.013 - 1/0.099)
= 1.67*10^-12 F
Apply, q = C*delta_V
= 1.67*10^-12*420
= 7.01*10^-10 C or 0.701 nC
B) Yes.
Beacuse, workdone by electric field on equipotential is zero. It means E is peprendicular to the equipotential surface.
C) Equipotential surfaces closer together when the magnitude of E is largest.