Question

Point charges Q1 = 2.5 µC and Q2 = 6.0 µC are located at r1 = (2.0î − 2.0ĵ + 6.0k) m and r2 = (8.0î + 7.0ĵ − 9.0k) m. What is the force (in N) of Q2 on Q1? (Express your answer in vector form.)

Answer 1

Q₁ = 2.5 x 10^-6 C

Q₂ = 6 x 10^-6 C

= 2 i - 2 j + 6 k

= 8 i + 7 j - 9 k

- = (2 i - 2 j + 6 k) - (8 i + 7 j - 9 k) = - 6 i - 9 j + 15 k

|- | = sqrt((- 6)² + (- 9)² + (15)²) = 18.5

force on Q₁ is given as

F = k Q₁ Q₂ (- ) /(|- |)³

inserting the values

F = (9 x 10⁹) (2.5 x 10^-6) (6 x 10^-6) (- 6 i - 9 j + 15 k) /(18.5)³

F = (21.32 x 10^-6) (- 6 i - 9 j + 15 k)

F = - (1.3 x 10^-4) i - (1.9 x 10^-4) j + (3.2 x 10^-4) k