Problem $1$: Indicate the direction of the forces exerted by the magnetic field on the moving charges at the instant shown in the figures. Express your answer in terms of hat$(),$hat$(),$ and hat$(k).$ Write zero if there is no force on the charge. Include the negative sign in front of the unit vector as needed.

a$.$ The direction of the magnetic force experienced by charge $1$ is:

b$.$ The direction of the magnetic force experienced by charge $2$ is:

c$.$ The direction of the magnetic force experienced by charge $3$ is:

d$.$ The direction of the magnetic force experienced by charge $4$ is: