Capacitors

Question 1

Capacitance

Answer 1

Charge stored per unit of potential difference across a capacitor C = Q/V.

Question 2

Farad

Answer 2

A unit of capacitance defined as one coulomb per volt.

Question 3

Capacitors in Series/Parallel

Answer 3

Series Equation is similar to PARALLEL Resistors but using Capacitance.

Parallel Equation is similar to SERIES Resistors but using Capacitance.

Question 4

Time Constant

Answer 4

The time taken for the p.d. / current / charge to decrease to 1/e (1/2.718 ~ 37%) its initial value.
x = xoe-t/CR when t = CR then x = xoe-1 which is x ≈3.7xo

The units that come from a circuit containing a capacitor (C) and a resistor (R) and are given by the Time Constant = CR.
CR = Q/V x V/I = Q/I
Q = It, hence CR = It/I = t (seconds).