Could someone PLEASE help me with these physics questions?

(5) (12 pts.) A metallic Sphere of radius 5 cm is charged such that the potential of its surface is 100 V (relative to innity). (a) In one or two sentences explain why the electric eld inside the conduct ing sphere is zero. (b) On the graph below draw a plot of the potential as a function of the distance from the center of the sphere. 100 V 0 5 cm 10 cm Distance FIGURE 3 (6) (10 pts.) A charge is accelerated from rest through a potential difference AV and then enters a uniform magnetic field oriented perpendicular to its path. The field deflects the particle into a circular arc of radius R. If the accelerating potential is tripled to 3AV, what will the radius of the circular arc be