Question

(a) Calculate the electric potential 0.340 cm from an electron.


(b) What is the electric potential difference between two pointsthat are 0.340 cm and 0.730 cm from an electron?


(c) How would the answers change if the electron were replaced witha proton?
The sign of answer (a) would change.
The sign of answer (b) would change.  
The sign of both answers would change.
Both answers would remain the same.

Answer 1

The potential at distance from a charge is, kg (9x10'° N-m'/C) -1.6x10-19 C) 0.340x10 m =-4.235x 10-7 V The electric potential at a distance 0.730 cm from an electron is, kO 9x109 N m2/C2-1.6x10-19 C 0.730x102 m =-1.97 x 10-7 The potential difference between two points that are 0.340 cm and 0.730 cm from an electron is =-1.97×10--(-4.23 5x 10-v 2.265x107 v If proton were replaced by the electron, sign of the all the above results would be change Therefore, the option: the sign of both answers would change is correct answer

The potential difference between the points 0.340 cm and 0.730 cm from a charge is equal to the potential at 0.730 cm - potential at 0.340 cm. In case of proton, the potential at 0.730 cm is positive and less than the positve potential at 0.340 cm. Hence, the difference of smaller potential - greater potential is a negative value. Hence, the sign of the potential difference changes if electron is replaced with proton.