\(\frac{L}{R}\) has the dimensions of time. Because \(\frac{L}{R}\) is the time constant of \(L-R\) circuit.
\(\therefore \left[\frac{L}{R}\right]=[ T ]\)
Charge \(=\) Capacitance \(\times\) Potential difference
\(Q=C V\)
and \({[Q]=[A T]}\)
\(\therefore \left[\frac{L}{R C V}\right]=\left[\frac{L}{Q}\right]\)
\(=\left[\frac{T}{A T}\right]\)
\(\left[\frac{L}{R C V}\right]=\left[A^{-1}\right]\)
Therefore, the correct option is (A): \([A^{-1}]\)
Dimensional Analysis is a process which helps verify any formula by the using the principle of homogeneity. Basically dimensions of each term of a dimensional equation on both sides should be the same.
Limitation of Dimensional Analysis: Dimensional analysis does not check for the correctness of value of constants in an equation.
Let us understand this with an example:
Suppose we don’t know the correct formula relation between speed, distance and time,
We don’t know whether
(i) Speed = Distance/Time is correct or
(ii) Speed =Time/Distance.
Now, we can use dimensional analysis to check whether this equation is correct or not.
By reducing both sides of the equation in its fundamental units form, we get
(i) [L][T]-¹ = [L] / [T] (Right)
(ii) [L][T]-¹ = [T] / [L] (Wrong)
From the above example it is evident that the dimensional formula establishes the correctness of an equation.