When can an electric field be measured at any point from the force on a stationary test charge at that point?

Electric field be measured at any point from the force on a stationary test charge at that point, when the force on the test charge is generated only by the coulomb field (E) of static charges.

Explanation:

Total force on a test charge is given as;

F = qE + q(V x B)

F = q(E + V x B)

Where;

F is the total force on the test charge

q is the test charge

E is the electric field

B is the magnetic field

V is the velocity of the test charge

F = q(E + V x B)

for a stationary test charge, V = 0

The equation above reduces to;

F = qE

Thus, electric field be measured at any point from the force on a stationary test charge at that point, when the force on the test charge is generated only by the coulomb field (E) of static charges.

answer and explanation;

i had this question and the answer was 3.15 miles.

martina travels from school to her mom's office. from there, she walks to school. after school, she walks to the library and then to a friends house before finally ending back at home. find martina's total distance traveled.

a) 0 miles  

b) 0.4 miles  

c) 1 mile  

d) 3.15 miles