Two cylindrical rods, of different material, are joined as shown. The rods have same cross section `(A)` and their electrical resistivities are `rho_(1) and rho_(2)`. When a current `I` is passed through the rods, a charge `(Q)` gets piled up at the junction boundary. Assuming the current density to be uniform throughout the cross section, calculate `Q`.
![image](https://learnqa.s3.ap-south-1.amazonaws.com/images/161289668715905365581612896687.png)