# R, L and C represent the physical quantities resistance, inductance and capacitance, respectively. Which one of the following combinations has the dimension of frequency?

1) 1/√RC

2) R/L

3) 1/LC

4) C/L

For RC circuits, the time constant is

τ=RC, it has the unit of time,

so,1/RC has a unit of frequency,

similarly for LC oscillations,
τ= √LC

for RL circuit, τ= L/R

so, 1/RC, R/L and 1/√LC has units of the frequency.