A protein molecule in an electrophoresis gel has a negative charge. The exact charge depends on the pH of the solution, but 30 excess electrons is typical. What is the magnitude of the electric force on a protein with the 30 excess electrons in a 1540 N/C electric field

7.401 * 10^(-15) N

Explanation:

30 electrons will have a charge:

30 * -1.6022 * 10^(-19) C

= - 4.806 * 10^(-18) C

The relationship between electric field and electric force is:

E = F/q

This means that force, F, is

|F| = |E|*|q|

|F| = |1540| * |-4.806 * 10^(-18)|

|F| = |-7401.24 * 10^(-18)|

|F| = 7.401 * 10^(-15) N

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west