RC circuit setup and capacitor physics
S
OPEN
R
V
s
+
−
C
V
C
Switch open →
V
C
=
V
0
+
+
+
+
+
+
+
+
+
+
+
q
E
initial
charge:
V
0
−
q
V
C
builds as charge
accumulates
V-I relationship
current–voltage law
i = C dv/dt
AC / changing V
dv/dt ≠ 0
→ i ≠ 0 — current flows
DC steady state
dv/dt = 0
→ i = 0 — open circuit
Charging curve — V
C
(t) = V
f
+ (V
0
− V
f
)e
−t/RC
R
1.0 kΩ
C
100 µF
V
f
5.00 V
V
0
0.0 V
τ = RC =
100.0
ms
Capacitor current i(t)