The dimension of RC is

The correct option is time.

To find the dimension of the product $RC$ (where $R$ is resistance and $C$ is capacitance), we can use the definitions of electrical resistance, capacitance, and electric current:

1. By Ohm's law, resistance ($R$) is defined as the ratio of potential difference ($V$) to current ($I$):

$R=\frac{V}{I}$

2. Capacitance ($C$) is defined as the ratio of charge ($Q$) to potential difference ($V$):

$C=\frac{Q}{V}$

3. Multiplying resistance and capacitance, the potential difference ($V$) cancels out:

$R\times C=\left(\frac{V}{I}\right)\times \left(\frac{Q}{V}\right)=\frac{Q}{I}$

4. Since electric current ($I$) is defined as the rate of flow of charge over time ($t$):

$I=\frac{Q}{t}\Rightarrow Q=I\times t$

5. Substituting this back into the expression for $RC$ gives:

$RC=\frac{I\times t}{I}=t$

Thus, the dimensional formula of $RC$ is that of time, which is represented as [T]. In physics, this product is also known as the capacitive time constant of an RC circuit.