Amagnetic field forms around a moving electric charge, resulting in a magnetic field.

which does this describe?

a.
how electric charges can be used to make current flow

b.
how electric charges can be used to create a magnetic field

c.
how a magnetic field can be used to generate an electric current

d.
how a magnetic field can be used to generate electrons

Need in all of themmm only answer if you know plsssss

Aresistor with an unknown resistance is connected in parallel to a 9 ω resistor. when both resistors are connected in parallel to an emf source of 21 v, the current through the unknown resistor is measured with an ammeter to be 4 a. what is the resistance of the unknown resistor? answer in units of ω.

Emmy kicks a soccer ball up at an angle of 45° over a level field. she watches the ball's trajectory and notices that it lands, two seconds after being kicked, about 20 m away to the north. assume that air resistance is negligible, and plot the horizontal and vertical components of the ball's velocity as a function of time. consider only the time that the ball is in the air, after being kicked but before landing. take "north" and "up" as the positive ‑ and ‑directions, respectively, and use ≈10 m/s2 for the downward acceleration due to gravity.