Eric created an electromagnet and this graph shows his results. What could Eric have changed in his electromagnet that caused the decrease in magnetic force from point A to point B? (You MUST give at least 3 possible reasons/changes in the electromagnet)

I already have 2 answers (The electric current going to the electromagnet could have went lower or he could have decreased the amount of coils around the metal if he was making a solenoid.) I just need one more. 20 POINTS.

The coulomb's law explains which of the following? select all the force between two charged objects is inversely proportional to the charge on each object. the force between two charged objects is directly proportional to the charge on each object. the force between two charged objects is directly proportional to the distance separating them. the force between two charged objects is inversely proportional to the square of the distance separat coulomb's law is similar to newton's 2nd law. if the force between two objects is f and the charge on both objects is doubled, the new force between the would now be 2f. if the force between two objects is 2f and the distance separating them is doubled, the new force between the objects would now o the be zf.

Four identical lab carts each have a mass of 200 kg. different masses are added to the carts and the velocities are measured. all carts move to the right.

The gun from the crime scene shows tool marks where the serial numbers are ground off. there are also tool marks on the bullets left behind. what information can the tool marks on the bullets and gun provide about the crime? what type of evidence does this information provide, individual or class?