'A radioactive element has a 0.5 probability of decaying to a more stable element after a particular time-span T.
What is the instantaneous decay rate per unit volume? In other words determine a general expression for the number of decay events occurring per unit volume between t=t1 and t=t2...
Thanks for just clearing that up for me. I've managed to find a question on this (I'm getting practise in before mid-year exams) however it deals in terms of charge density. Is it just as simple as finding Q in terms of the sphere (volume of shell at such and such density).
Ok if you have a spherical shell of radius R with an even distribution of charge then outside the shell at a distance r where r>R I get that the shell can be treated as a point charge and inside the sphere (r<R) the electric potential will be constant.
All my notes cover when the shell has no...