Hi there!
We can solve for the time constant using the following:
[tex]\tau = RC[/tex]
τ = Time Constant (s)
R = Resistance (Ω)
C = Capacitance (F)
Simply plug in the values. Remember that:
4.7 μF = 4.7 * 10⁻ ⁶ F = 0.0000047 F
22kΩ = 22 * 10³ Ω= 22000Ω
Solve:
[tex]\tau = 0.0000047 * 22000 = \boxed{0.1034 s}[/tex]