Which of the following locations has the largest electric field? a)0.4 cm from a +3.0 uc point charge b)0.2 cm frm a +1.5 uc point charge c)0.4 cm from a +6.0 uc point charge d)0.2 cm from a +3.0 uc point charge

Electric field is proportional to q/d^2, where q is the magnitude of the charge and d is the distance. Since all the given units are identical, we can just compare their relative magnitudes without calculating for the exact values.
A) 3/(0.4)^2 = 18.75
B) 1.5/(0.2)^2 = 37.5
C) 6/(0.4)^2 = 37.5
D) 3/(0.2)^2 = 75
Therefore, choice D has the largest electric field of all.

The charge of an ion with 55 protons and 52 electrons is +3. the reason is because protons are positive, and there are three more than the amount of negative electrons.