A pacemaker uses an RC circuit for timing. (a) If the pacemaker is to operate at 72 beats/min,
and if the circuit “fires” when the capacitor is 65%
charged, what must the time constant be?
(b) When C 5 7.50 mF, what value of resistance should
be used?

Athin nonconducting rod with a uniform distribution of positive charge q is bent into a circle of radius r. the central perpendicular axis through the ring is a z-axis, with the origin at the center of the ring. a) what is the magnitude of the electric field due to the rod at z = 0? n/c (b) what is the magnitude of the electric field due to the rod at z = infinity? n/c (c) in terms of r, at what positive value of z is that magnitude maximum? r (d) if r = 4.00 cm and q = 9.00 µc, what is the maximum magnitude? n/c