Please Help!

in decimals

Q1.

For a ring of radius R and charge Q, what is the on-axis electric potential in volts a distance 2 below the ring using the same conventions as in Example 26.3 of our book? Take Q = 1 nC (1 nanocoulomb}, R = 1 meter, and let 2 be a distance 1 meter below the ring's center. For an RC discharging circuit that starts out with charge Q, how long does it take for the charge to decrease by 90% (q = Q/ 10)? On dimensional grounds, the answer is a dimensionless number times R C {the resistance multiplied by the capacitance of the circuit). What is this dimensionless number? What is the equivalent resistance of this circuit? The answer is a dimensionless number times R (where R is the resistance of all the individual resistors as shown). What is this dimensionless number