Why the activity of a radioactive sample reduces with time?

What are the factors that affect the resistance of a wire?

Which of the following is not am example of a polymer? protein nylon kevlar concreta

The electric field between square plates of a parallel-plate capacitor has magnitude e. the potential across the plates is maintained with constant voltage by a battery as they are pulled apart to twice their original separation, which is small compared to the dimensions of the plates. the magnitude of the electric field between the plates is now equal to a)e b)e/4 c)e/2 d)4e e)2e