A current is flowing in a wire in direction 3i + 4j where the direction of the magnetic field is 5j + 12k. The force on the wire is: a. 0.71(i + j).
b. 0.78i - 0.58j + 0.24k.
c. 0.78i + 0.58j - 0.24k.
d. 0.78i + 0.58j + 0.24k.

F = 0.768 i ^ - 0.576 j ^ + 0.24 k ^

the correct answer is "b"

Explanation:

The magnetic force is

          F = i l x B

The bold are vectors, in this case they give us the direction of the current and the magnetic field, for which we can solve as a determinant

resolver

     F = i ^ (4 12 - 0) + j ^ (0- 3 12) + k ^ (3  5 - 0)

     F = i (48 i ^ - 36 j ^ + 15 k⁾

in this case i is the value of the current flowing through the cable

     i = 16 mA = 0.016 A

     F = 0.768 i ^ - 0.576 j ^ + 0.24 k ^

When reviewing the different answers, the correct answer is "b"

that would be because of both gravity and friction. so     c