The neutral identical aluminium spheres A and B are hanged freely such that they are in contact, as shown in the figure. A negatively charged rod is brought close to the spheres as shown.
![negative charge brought close to spheres](https://www.easyelimu.com/images/form_4_past_papers/Term_3_2021/Mocks_/physics/negative_charge_brought_close_to_spheres.JPG)
One of the spheres B is earthed momentarily by touching with finger and then the rod is withdrawn. State and explain the observation made.