A cephalopod with an external shell is

Which of the following cephalopods possesses an external shell ?

Cephalopod with exoskeleton :-

With what the hard external shell of snails, conches and the like is made of?

Siphon of cephalopods is connected internally to

Siphon of cephalopods is connected internally to

Siphon of cephalopods is connected internally to

Two thin conducting shells of radii R and 3R are as shown in the fig. External shell carries a charge +Q and inner shell neutral. The inner shell is earthed with the help of a switch S . Then

Two thin conducting shells of radii R and 3R are as shown in the fig. External shell carries a charge +Q and inner shell neutral. The inner shell is earthed with the help of a switch S . Then

Show that the intensity of the electric field at an external point due to a uniformly charged thin spherical shell is the same as if the whole charge were situated at its centre.