Question

L, C and R represent the physical quantities inductance, capacitance and resistance respectively. Which of the following combinations have dimensions of frequency?

• A. $\frac{1}{RC}$
• B. $\frac{R}{L}$
• C. $\frac{1}{\sqrt{LC}}$
• D. $\frac{C}{L}$

Answer 1

Answer: (A), (B), (C)

The correct options are
A $\frac{1}{RC}$
B $\frac{R}{L}$
C $\frac{1}{\sqrt{LC}}$

For RC circuits, time constant is,
$\tau =RC$ has unit of time,

so, $\frac{1}{RC}$ has a unit of frequency,

similary for LC oscillations,
$\tau =\sqrt{LC}$

for RL circuit, $\tau =\frac{L}{R}$
so,

$\frac{1}{RC}$ , $\frac{R}{L}$ and $\frac{1}{\sqrt{LC}}$ has units of frequency.