A test charge is placed at a distance of 2.5 * 10-2 meters from a charge of 6.4 * 10-5 coulombs. What is the electric field at the test charge? (k = 9.0 * 109 newton·meter2/coulomb2)

Using the formula: E = kQ / d² where E is the electric field, Q is the test charge in coulomb, and d is the distance.

E = kQ / d²

k = 9 x 10^9 N-m²/C²

Q = 6.4 x 10^-5 C

d = 2.5 x 10^-2 m

Substituting the given values to the equation, we have:

E = (9 x 10^9) (6.4 x 10^-5) / (2.5 x 10^-2) ²

Electric field at the test charge is 921600000 N/C