1. The problem is to rationalise the denominator of the expression $\frac{1}{\sqrt{11}}$. 2. To remove the square root from the denominator, multiply both the numerator and denominator by $\sqrt{11}$: $$\frac{1}{\sqrt{11}} \times \frac{\sqrt{11}}{\sqrt{11}} = \frac{\sqrt{11}}{11}$$ 3. The expression $\frac{\sqrt{11}}{11}$ has no radical in the denominator and is in simplest form. 4. Therefore, the rationalised form of $\frac{1}{\sqrt{11}}$ is $\frac{\sqrt{11}}{11}$.