Two plane mirrors M_1 and M_2 are at right angle to each other shown. A point source ' P ' is placed at ' a ' and ' 2 a ' meter away from M_1 and M_2…

Two plane mirrors $\displaystyle \mathrm{M}_1$ and $\displaystyle \mathrm{M}_2$ are at right angle to each other shown. A point source ' P ' is placed at ' a ' and ' $\displaystyle 2$ a ' meter away from $\displaystyle \mathrm{M}_1$ and $\displaystyle \mathrm{M}_2$ respectively. The shortest distance between the images thus formed is : (Take $\displaystyle \sqrt{5}=2.3$ )