A point charge of -11 [Coulombs] is placed inside a spherical conducting shell with net charge of 5 [Coulombs]. Calculate the net charge on the outer surface of the conducting shell. Enter your answer without units (example 100 for 100 [Coulombs] or -100 for -100 [Coulombs] ).

20 C

Explanation:

To do this, is pretty easy, we just need to do a little reasoning of what is happening.

When any charge  called q is placed inside this metallic shell which is spheric, all the opposite and even equal charges are induced on the inner and outer surface of the shell. Hence, we can say that if in the inner shell we have +q, in the outer will be -q.

Now, here we have the shell with 5 C, and when the charge of -11 C is placed inside the shell we can have the following changes on the inner surface and the outer surface:

Inner surface: +11 C

Outer surface: 9 + 11 = 20 C

Hope this helps