A large solid sphere of diameter d attracts a small particle with a force F. If the central portion of the sphere of diameter `(d)/(2)` be removed leaving behind a cavity, then the new force of attraction becomes

A metallic sphere of diameter D has a cavity of diameter d at its centre. If the sphere is heated, the diameter of the cavity will:

A solid sphere of radius R gravitationally attracts a particle placed at 3R form its centre with a force F_(1) . Now a spherical cavity of radius ((R)/(2)) is made in the sphere (as shown in figure) and the force becomes F_(2) The value of F_(1) : F_(2) is:

A large solid sphere of diameter 15m is melted and recast into several small spheres of diameter 3m . What is the percentage increase in the surface area of the smaller spheres over that of the large sphere?

Two small identical spheres having charges +10 muC and - 90muC attract each other with a force of F newton . If they are kept in contant and then separated by the same distance, the new force between them is -

Two charged spheres when placed in air attract with a force F. Keeping the distance between the charges constant, the spheres are immersed in a liquid of relative permittivity K. Then the spheres will

The centres of two identical small conducting spheres are 1m apart. They carry charge of opposite kind and attract each other with a force F. When they are connected by a conducting thin wire they repel each other with a force F//3 . What is the ratio of magnitude of charge carried by the sphere initially ?