How does increasing the amount of charge on an object affect the electric force it exerts on another charged object?

Edward tolman explained the results of his study by theorizing that the rats were learning about the maze during every trial but they a. were agitated because other groups were getting reinforcement b. could not remember how to demonstrate it without reinforcement c. were not motivated to demonstrate it without reinforcement d. seemed to be too lazy to actually work without reinforcement

Which of the following changes will result in a stronger electromagnet? a. using fewer coils of wire b. using a higher voltage c. using a shorter nail d. using a longer wire

Does heating a metal wire increase or decrease its electrical resistance? why?