13) Three charges are at the corners of an equilateral triangle of side length 0.5m as shown. What is the magnitude of the net electric field produced by these charges at the center of the triangle? 15. Atomic nuclei has dimensions of the order 10-15m. If two protons in a nucleus are separated by a distance of 5 x 10-15m, what is the magnitude of the electric force between them?

13. Zero 

15. 9.216 N

Step-by-step explanation

13. The net electric field produced by all the three identical charges at the center of an equilateral triangle would be zero due to the cancellation of the field of all charges by each other.

15. 

The electric force between two point charges placed at distance r is given by F=r2kq1?q2??.

Here given,

charges are protons so their charge would be e = 1.6 x 10^-19 C

and the distance between them is r = 5 x 10^-15 m

So force between them would beF=r2ke2?=(5×10−15)29×109×(1.6×10−19)2?

 ⇒F=9.216N

and it will be repulsive force.

Please see attached file